Same issue for me, self-hosted ghost instance. Running on Digital Ocean, used their installation guide. Running for over 4 years. This issue started after upgrade 5.72.0 (I believe), at least I couldn’t upload images or videos after that point. I’ve run ghost doctor, no issues found. I’ve looked at permissions.
I can upload images to a gallery, but when I upload images to a gallery, they do not appear on preview and they are not saved in the draft (if I exit the edit mode).
This is also true for files. I can upload, but they don’t actually upload.