DateTime::modify('-1 second') goes 59 minutes later on DST

[kylekatarnls]

Description

The following code:

<?php
echo (new DateTime('2025-03-30 00:59:59', new DateTimeZone('Europe/London')))
    ->modify('+1 second')
    ->modify('-1 second')
    ->format('Y-m-d H:i:s.u e T');

Resulted in this output:

2025-03-30 02:59:59.000000 Europe/London BST

But I expected this output instead:

2025-03-30 00:59:59.000000 Europe/London GMT

Which is also the output we get when executing (since PHP 8.1, before that add/sub interval and modify gave the same output):

echo (new DateTime('2025-03-30 00:59:59', new DateTimeZone('Europe/London')))
    ->add(new DateInterval('PT1S'))
    ->sub(new DateInterval('PT1S'))
    ->format('Y-m-d H:i:s.u e T');

PHP Version

PHP 8.5.3

Possibly related to

#15880