solidity v0.8.15：ETH 主网上的需求和映射问题

Question

I'm working on a NFT management contrat; I can see everything works fine on rinkeby testnet, but when I'm calling the same functions on mainnet, I get errors many false errors with require. code was compiled on REMIX Ide;

Here is an example:

mapping(address => mapping(uint => uint8) public handledNfts;

mapping(bytes32 => uint8) public usedHashes;

function create(address contractAddress, uint tokenId, bytes32 hash) external
{
    uint8 vCheck = usedHashes[hash];

    require(vCheck!=1, "Bad hash");    // sometimes it has false-positive

    usedHashes[ hash ] = 1;

    uint8 vCheck = handledNfts[contractAddress][tokenId];
    
    require(vCheck!=1, "Already created");    // False-positive sometimes also

    handledNfts[contractAddress][tokenId] = 1;



    //--- DO SOMETHING ....
}

So when I'm on rinkeby any call to create will work. However on mainnet, the create function returns a "Bad hash" or "Already closed" for no real reason, but sometimes in works like a charm.

So I don't know what's the problem on mainnet for a code which works fine from testnet?

It's strange because the handledNfts[contractAddress][tokenId] should not be at ==1 when starting using the contrat. However solidity says the hash has already been used or the nft says to be already managed, when it's not true. Sometimes it works and sometimes it doesn't. Most of the time it doesn't

The hash using in the create function is always unique for each call.

Can someone help me find a solution on that instability, please? It seems like mapping objects with a require don't work properly with me.

I compile the code through remix directly, with solidity v0.8.15 https://remix.ethereum.org/#optimize=true&runs=200&evmVersion=null&version=soljson-v0.8.15+commit.e14f2714.js

stangely also, I'm forced to use a variable to access a mapping object then use that variable; so a code like this is buggy on me many time:

require(usedHashes[hash]!=1, "Hash already used"); <-- buggy on mainnet

Any help please?

Answer 1

I understand what happened. I've been front-runned by a MEV BOT. It detected an ETH transaction was sent from my smartcontract, and sent a copy-cat of the transaction earlier than mine.

I've put counter-actions to avoid it. it's okay now.