日期时间格式显示错误的日期

Question

I'm having an odd one which is breaking an invoicing script. I have a payment date of 31st August 2019 and this person is to then be paid on the same day each week which means that this would be every Saturday. However when i enter this as a new DateTime object when formatted with l it says Sunday. PHP is 7.1

$fpd = new DateTime( date( 'Y-m-d 00:00:00', strtotime( '2019-08-31' ) ) );
var_dump( $fpd ); // returns 2019-08-31 00:00:00.000000 in the date section
echo $fpd->format( 'l' ); returns Sunday

Whats going on? is this just me with this? If i format the date to show the Day i get this (assuming $fpd is as above)

echo $fpd->format( 'g:ia \o\n l jS F Y' ); returns 12:00am on Sunday 1st September 2019

so confused how can 0h0m on 31st August be 24 hours later?

thanks

Edit: I should point out I'm using WAMP64 and in the uk. I tried using php 7.0 but the same result, php 5.6 is not an option as code is php 7 complient. I tried just using 'Ymd' but it saves the time in the DateTime object anyway

$fpd = {DateTime)[3]
date => "2019-08-31 00:00:00.000000",
timezone_type => {int}3,
timezone => "Europe/London"

$fpd->format( 'l' ) still shows Sunday

Further Edit: Corrected (string) in above code to a var_dump. running this standalone in its own test.php file works and shows the day as Saturday but it uses the UTC timezone.

Answer 1

This returns Saturday (Php 7.3) tested

<?php
 $fpd = new DateTime( date( 'Y-m-d', strtotime( '2019-08-31' ) ) ); 
 echo $fpd->format( 'l' );
 echo $fpd->format( 'l' ); //returns Sunday
 echo $fpd->format( 'g:ia \o\n l jS F Y' );
 ?>

Answer 2

So it turned out the maths was wrong due to today being after the clocks changed. I removed any times throughout and the code is now working correctly. Big up to @davidev & @Tschallacka for pointing me in the right direction