PHP-8 Compatibility ?

I have got so many error-messages when trying to work on events, that it almost becomes impossible to so.
In the global-config I've set error-readings to "off", but that doesn't help. I have checked other Extensions, but there are no errors on them.
The errors only occur in backend, when trying to add or to edit one event.

Error says:
"Deprecated: Function strftime() is deprecated in ...\libraries\src\HTML\HTMLHelper.php on line 1199
and there is another (different)message.
   - it occurs specifially on places where there is calender (at least it looks like that)
   - I tried to put some screenshots  as attachment, not sure if that works.

Since I purchased this Extension only yesterday ... I'm obviously not a happy-chappy.

I'm working on Joomla-4.1.5 (brand new installation) on xampp with PHP-8.14
Is Event-Booking capable of running on that, or should I use an older PHP-version ... or what else could be the problem?

Thanks for any help in advance