I have this same issue. I upgraded our PHP to 8.0.10 and now it looks like WordPress is unable to generate thumbnails for images I upload into the media library. I tried a thumbnail regenerating plugin and that did not work either. I dropped the PHP version down to 7.4.11 and now I can get it to create thumbnails by adding an image, going in to edit the image, rotate it left, then rotate it back to the right, then save the image. That workaround did not work on version 8.0.10.
If you need more information to help with this let me know.
Thanks
