I can't stand imgur. You can't upload photos without an account, and the adds are as obnoxious nails on a chalkboard. Most of the time when I post images here they're obviously related to bitcoin, and I don't need some third party image hosting company tracking my financial habits.
I never used imgur with account for posting images and I have been using it for years without any issues.
Few times it happened that imgur was not working I used imgbb or some other alternative servers for uploading images.
You can even find some programs that can help you to upload images faster directly from your OS and choose any server you want.
imgbb is a pretty decent image hosting site, and no need for KYC, lol. Maybe it is imgbb that's causing the issue. Right now I can see all my images that I've posted, but they've been problematic for at least two, maybe three weeks.
I saw recently that forum is showing image missing messages but I didn't check if the source server has issue or something else forum related.
If you want to be sure your images will be available you can run your own server with self-hosted image hosting.