Performance downgrade after upgrading EF Core 5 to 6

Question

I have quite complex linq query with many joins which works really fast with Entity Framework Core 5 (around 10 ms) on SQL Server 2017 (v14.0.3436.1).

After upgrading to EF Core 6 it takes around 5 minutes (same database). I found out that the only difference in the generated SQL query is missing last order by clause, which is new "feature" in EF Core 6 - https://docs.microsoft.com/en-us/ef/core/what-is-new/ef-core-6.0/whatsnew#remove-last-order-by-clause-when-joining-for-collection

I just cannot understand how it could be slower if I remove last order by clause. I would expect otherwise. Does anybody have any idea what can cause this?

The workaround for now is to use .AsSplitQuery() which splits query and works fast again.

This is the fast SQL query, but when I remove the [t0].[RoleID0] at the end, it significantly slows down (10 ms to 5 min).

SELECT [c].[SpecimenSignatureID], [c].[ChangeSum], [c].[CreationTime], [c].[DivisionCode], [c].[EfficiencyDate], [c].[IsArchived], [c].[IsStamp], [c].[LastChangeOrExchangeTime], [c].[LastModificationTime], [c].[LicenceInternalID], [c].[NonemissiveEnabled], [c].[PersonTypeCode], [c].[PowerExpiration], [c].[ProductCancelDate], [c].[ProductLicencePermissions], [c].[StampNumbers], [c].[SubdivisionCode], [c].[ValidTo], [c].[Version], [c].[WayOfDispose], [c0].[LicenceInternalID], [c0].[LicenceID], [c0].[LicenceNumber], [c1].[ProductID], [c1].[AgreementNumber], [c1].[BankCode], [c1].[EffectiveDate], [c1].[NormalizedAgreementNumber], [c1].[Number], [c1].[Prefix], [c1].[ProductTypeCode], [c1].[ProductTypeCodeLegacy], [c1].[SpecificSymbol], [c1].[SpecimenSignatureID], [t0].[RoleID], [t0].[AdditionalInformation], [t0].[Order], [t0].[PartySpecificID], [t0].[RoleTypeCode], [t0].[SpecimenSignatureID], [t0].[SuperiorRoleID], [t0].[ValidFrom], [t0].[ValidTo], [t0].[PartySpecificID0], [t0].[Age], [t0].[Incompetent], [t0].[LastModificationTime], [t0].[MatricId], [t0].[PartyID], [t0].[ServicingCategoryCode], [t0].[UnderLegalAge], [t0].[Verified], [t0].[PartyID0], [t0].[BirthDate], [t0].[Cluid], [t0].[Incompetent0], [t0].[IncompetentValidityDate], [t0].[LastModificationTime0], [t0].[MajorityDate], [t0].[PersonTypeCode], [t0].[RelatedPartyID], [t0].[ServicingCategoryCode0], [t0].[UnderLegalAge0], [t0].[PartyID1], [t0].[BirthDate0], [t0].[Cluid0], [t0].[Incompetent1], [t0].[IncompetentValidityDate0], [t0].[LastModificationTime1], [t0].[MajorityDate0], [t0].[PersonTypeCode0], [t0].[RelatedPartyID0], [t0].[ServicingCategoryCode1], [t0].[UnderLegalAge1], [t0].[PartySpecificID1], [t0].[BirthNumber], [t0].[FirstName], [t0].[IdentificationDocumentCode], [t0].[IdentificationDocumentID], [t0].[LastName], [t0].[Nationality], [t0].[NormalizedFirstName], [t0].[NormalizedLastName], [t0].[TitleAfter], [t0].[TitleBefore], [t0].[PartySpecificID2], [t0].[Identification], [t0].[Name], [t0].[NormalizedName], [t0].[PartySpecificID3], [t0].[City], [t0].[Country], [t0].[Street], [t0].[ZipCode], [t0].[PartySpecificID4], [t0].[Age0], [t0].[Incompetent2], [t0].[LastModificationTime2], [t0].[MatricId0], [t0].[PartyID2], [t0].[ServicingCategoryCode2], [t0].[UnderLegalAge2], [t0].[Verified0], [t0].[PartySpecificID00], [t0].[BirthNumber0], [t0].[FirstName0], [t0].[IdentificationDocumentCode0], [t0].[IdentificationDocumentID0], [t0].[LastName0], [t0].[Nationality0], [t0].[NormalizedFirstName0], [t0].[NormalizedLastName0], [t0].[TitleAfter0], [t0].[TitleBefore0], [t0].[PartySpecificID10], [t0].[Identification0], [t0].[Name0], [t0].[NormalizedName0], [t0].[PartySpecificID20], [t0].[City0], [t0].[Country0], [t0].[Street0], [t0].[ZipCode0], [t0].[RoleID0], [t0].[AdditionalInformation0], [t0].[Order0], [t0].[PartySpecificID30], [t0].[RoleTypeCode0], [t0].[SpecimenSignatureID0], [t0].[SuperiorRoleID0], [t0].[ValidFrom0], [t0].[ValidTo0]
FROM [SpecimenSignature] AS [c]
LEFT JOIN [Licence] AS [c0] ON [c].[LicenceInternalID] = [c0].[LicenceInternalID]
LEFT JOIN [Product] AS [c1] ON [c].[SpecimenSignatureID] = [c1].[SpecimenSignatureID]
LEFT JOIN (
    SELECT [c2].[RoleID], [c2].[AdditionalInformation], [c2].[Order], [c2].[PartySpecificID], [c2].[RoleTypeCode], [c2].[SpecimenSignatureID], [c2].[SuperiorRoleID], [c2].[ValidFrom], [c2].[ValidTo], [c3].[PartySpecificID] AS [PartySpecificID0], [c3].[Age], [c3].[Incompetent], [c3].[LastModificationTime], [c3].[MatricId], [c3].[PartyID], [c3].[ServicingCategoryCode], [c3].[UnderLegalAge], [c3].[Verified], [c4].[PartyID] AS [PartyID0], [c4].[BirthDate], [c4].[Cluid], [c4].[Incompetent] AS [Incompetent0], [c4].[IncompetentValidityDate], [c4].[LastModificationTime] AS [LastModificationTime0], [c4].[MajorityDate], [c4].[PersonTypeCode], [c4].[RelatedPartyID], [c4].[ServicingCategoryCode] AS [ServicingCategoryCode0], [c4].[UnderLegalAge] AS [UnderLegalAge0], [c5].[PartyID] AS [PartyID1], [c5].[BirthDate] AS [BirthDate0], [c5].[Cluid] AS [Cluid0], [c5].[Incompetent] AS [Incompetent1], [c5].[IncompetentValidityDate] AS [IncompetentValidityDate0], [c5].[LastModificationTime] AS [LastModificationTime1], [c5].[MajorityDate] AS [MajorityDate0], [c5].[PersonTypeCode] AS [PersonTypeCode0], [c5].[RelatedPartyID] AS [RelatedPartyID0], [c5].[ServicingCategoryCode] AS [ServicingCategoryCode1], [c5].[UnderLegalAge] AS [UnderLegalAge1], [c6].[PartySpecificID] AS [PartySpecificID1], [c6].[BirthNumber], [c6].[FirstName], [c6].[IdentificationDocumentCode], [c6].[IdentificationDocumentID], [c6].[LastName], [c6].[Nationality], [c6].[NormalizedFirstName], [c6].[NormalizedLastName], [c6].[TitleAfter], [c6].[TitleBefore], [c7].[PartySpecificID] AS [PartySpecificID2], [c7].[Identification], [c7].[Name], [c7].[NormalizedName], [c8].[PartySpecificID] AS [PartySpecificID3], [c8].[City], [c8].[Country], [c8].[Street], [c8].[ZipCode], [t].[PartySpecificID] AS [PartySpecificID4], [t].[Age] AS [Age0], [t].[Incompetent] AS [Incompetent2], [t].[LastModificationTime] AS [LastModificationTime2], [t].[MatricId] AS [MatricId0], [t].[PartyID] AS [PartyID2], [t].[ServicingCategoryCode] AS [ServicingCategoryCode2], [t].[UnderLegalAge] AS [UnderLegalAge2], [t].[Verified] AS [Verified0], [t].[PartySpecificID0] AS [PartySpecificID00], [t].[BirthNumber] AS [BirthNumber0], [t].[FirstName] AS [FirstName0], [t].[IdentificationDocumentCode] AS [IdentificationDocumentCode0], [t].[IdentificationDocumentID] AS [IdentificationDocumentID0], [t].[LastName] AS [LastName0], [t].[Nationality] AS [Nationality0], [t].[NormalizedFirstName] AS [NormalizedFirstName0], [t].[NormalizedLastName] AS [NormalizedLastName0], [t].[TitleAfter] AS [TitleAfter0], [t].[TitleBefore] AS [TitleBefore0], [t].[PartySpecificID1] AS [PartySpecificID10], [t].[Identification] AS [Identification0], [t].[Name] AS [Name0], [t].[NormalizedName] AS [NormalizedName0], [t].[PartySpecificID2] AS [PartySpecificID20], [t].[City] AS [City0], [t].[Country] AS [Country0], [t].[Street] AS [Street0], [t].[ZipCode] AS [ZipCode0], [t].[RoleID] AS [RoleID0], [t].[AdditionalInformation] AS [AdditionalInformation0], [t].[Order] AS [Order0], [t].[PartySpecificID3] AS [PartySpecificID30], [t].[RoleTypeCode] AS [RoleTypeCode0], [t].[SpecimenSignatureID] AS [SpecimenSignatureID0], [t].[SuperiorRoleID] AS [SuperiorRoleID0], [t].[ValidFrom] AS [ValidFrom0], [t].[ValidTo] AS [ValidTo0]
    FROM [Role] AS [c2]
    INNER JOIN [PartySpecific] AS [c3] ON [c2].[PartySpecificID] = [c3].[PartySpecificID]
    INNER JOIN [Party] AS [c4] ON [c3].[PartyID] = [c4].[PartyID]
    LEFT JOIN [Party] AS [c5] ON [c4].[RelatedPartyID] = [c5].[PartyID]
    LEFT JOIN [Person] AS [c6] ON [c3].[PartySpecificID] = [c6].[PartySpecificID]
    LEFT JOIN [Organization] AS [c7] ON [c3].[PartySpecificID] = [c7].[PartySpecificID]
    LEFT JOIN [Address] AS [c8] ON [c3].[PartySpecificID] = [c8].[PartySpecificID]
    LEFT JOIN (
        SELECT [c9].[PartySpecificID], [c9].[Age], [c9].[Incompetent], [c9].[LastModificationTime], [c9].[MatricId], [c9].[PartyID], [c9].[ServicingCategoryCode], [c9].[UnderLegalAge], [c9].[Verified], [c10].[PartySpecificID] AS [PartySpecificID0], [c10].[BirthNumber], [c10].[FirstName], [c10].[IdentificationDocumentCode], [c10].[IdentificationDocumentID], [c10].[LastName], [c10].[Nationality], [c10].[NormalizedFirstName], [c10].[NormalizedLastName], [c10].[TitleAfter], [c10].[TitleBefore], [c11].[PartySpecificID] AS [PartySpecificID1], [c11].[Identification], [c11].[Name], [c11].[NormalizedName], [c12].[PartySpecificID] AS [PartySpecificID2], [c12].[City], [c12].[Country], [c12].[Street], [c12].[ZipCode], [c13].[RoleID], [c13].[AdditionalInformation], [c13].[Order], [c13].[PartySpecificID] AS [PartySpecificID3], [c13].[RoleTypeCode], [c13].[SpecimenSignatureID], [c13].[SuperiorRoleID], [c13].[ValidFrom], [c13].[ValidTo]
        FROM [PartySpecific] AS [c9]
        LEFT JOIN [Person] AS [c10] ON [c9].[PartySpecificID] = [c10].[PartySpecificID]
        LEFT JOIN [Organization] AS [c11] ON [c9].[PartySpecificID] = [c11].[PartySpecificID]
        LEFT JOIN [Address] AS [c12] ON [c9].[PartySpecificID] = [c12].[PartySpecificID]
        LEFT JOIN [Role] AS [c13] ON [c9].[PartySpecificID] = [c13].[PartySpecificID]
    ) AS [t] ON [c5].[PartyID] = [t].[PartyID]
    WHERE [c2].[RoleTypeCode] IN ('AAA', 'BBB') OR ([c4].[Cluid] = 'XXX')
) AS [t0] ON [c].[SpecimenSignatureID] = [t0].[SpecimenSignatureID]
WHERE EXISTS (
    SELECT 1
    FROM [Role] AS [c14]
    INNER JOIN [PartySpecific] AS [c15] ON [c14].[PartySpecificID] = [c15].[PartySpecificID]
    INNER JOIN [Party] AS [c16] ON [c15].[PartyID] = [c16].[PartyID]
    WHERE ([c].[SpecimenSignatureID] = [c14].[SpecimenSignatureID]) AND ([c16].[Cluid] = 'XXX'))
ORDER BY [c].[SpecimenSignatureID], [c0].[LicenceInternalID], [c1].[ProductID], [t0].[RoleID], [t0].[PartySpecificID0], [t0].[PartyID0], [t0].[PartyID1], [t0].[PartySpecificID1], [t0].[PartySpecificID2], [t0].[PartySpecificID3], [t0].[PartySpecificID4], [t0].[PartySpecificID00], [t0].[PartySpecificID10], [t0].[PartySpecificID20], [t0].[RoleID0]