[bug?] Could not find class definition for name "In2code\Powermail\Domain\Model\DateTime"

[thomasrawiel]

(TYPO3 12.4.23, powermail 12.5.0, php 8.3.11 and 8.3.13)

Using the Page module, I got this error on a page containing Answers and Mails:

#1476045117 TYPO3\CMS\Extbase\Persistence\Generic\Exception\InvalidClassException
Could not find class definition for name "In2code\Powermail\Domain\Model\DateTime". This could be caused by a mis-spelling of the class name in the class definition.

The stacktrace points to the Classes/Hook/PluginPreviewRenderer (line 64)

When I delete the Mail records the error disappears.

I narrowed it down to Domain/Model/Mail.php line 82:
If I change the crdate property to @var \DateTime instead of @var DateTime the error also disappears and the plugin preview is rendered properly

Funnily enough, on my local ddev (php 8.3.12) the error doesn't happen.

So, not sure if it's really a bug or if it's something on our server