Firstly this is more of an FYI post, even though I am hoping there is a simple fix for the problem, since I seem to recall I am just about the only one using Pale Moon to browse these forums. Secondly the last time I can confirm via one of my posts that I was able to upload an image to the forums using the Pale Moon browser was on November 22. All of the images I have uploaded since then have either been directly from my phone, using the Chrome browser, or by letting the forum edit my post and save an image to the server. Letting the server edit my post to upload the image has only been done two or three times in the last 5 days.
Even though my current version needs to be updated the image uploader is working fine using Firefox.
So far I have not had trouble when I was using Firefox or Chrome. I am almost positive it was still hanging as recently as yesterday? No clue if it was fixed on the Discourse side or the browser side but it works for now.