Tested 1.6.5a on my WAMP (PHP 8.1.1) test environment. In my case it adds a , (comma) at the end of aperture e.g. "f/4," instead of "f/4".

Thanks, have to take another look. Really inconvenient new behaviour of PHP 8… In my tests this didn't happen…

Sadly it seems we cannot reproduce it so far. Please review the values in the image itself and what ends up in the db.

Checked the image. The value(s) are the same as with older pictures that I uploaded with a previous version of Zenphoto. Just saw that also the focal length gets a comma so it shows "27, mm" (DB value for EXIFFocalLength is what I see).
Finally I tried 2 other images an older one and one of the dame series as the first one. They do not use the comma. Wonder what went wrong with the one image. Well I think it can be ignored then.

Something must be different. With "standard" values we cannot reproduce it with various images from various sources so far.

Can you link or send one of the image so we can try exactly those?

I deleted the image and uploaded it again. Now all values are correct. It's not reproducable for me as well. Very strange.
Here is the link to the image http://www.paledog.de/Temp/1928-Mercedes-Benz-630-K-La-Baule-Torpedo-by-Saoutchik_front.jpg

Okay, then probably the data was not refreshed properly but a re-upload should not be necessary actually… Strange. Thanks, will test your image nevertheless just in case we missed anything.