We hit this same problem. I have a wrapper div with "align-center" but the styles applied do not center the image. The "margin:0 auto" does not work for my site. I cannot figure out why. There is no class applied on the image itself.
I was able to workaround it by adding "text-align:center" to the "align-center" class.
Pasqualle's comment in #18 saved us. We've spent days on a complicated D9->D10 upgrade and drupal/group broke the site after we manually used composer to update from drupal/group 1.x to 2.x. We found nothing helpful in the release notes.
The attitude of some developers in this thread is not helpful.