As per the main meta post - there's a risk of images hosted on the 'main' imgur instance (as opposed to the stack exchange one) being deleted due to changes in their TOS. Images uploaded anonymously will be deleted, and there's no real way to check which images fall under that.
There's a hair under 2000 posts that need going through and fixing according to SEDE - there may be some disruption to the front page as these are fixed. Using search may be a better option
Search for the url
Search for posts with code containing i.imgur.com (checked through)
Search for i.imgur.com
Some of these need resizing, and I'm not sure what to do with some of the gifs yet, since its not a simple upload - so its best effort first.
If you want to assist in fixing it - let us know, and if you're a user with only suggested edit abilities and the edits are not validated, you can generally find me or other users in the site chatroom to assist.
I used an answer with a table to keep track on pets - another site I moderate, and this... is unwieldy at scale, and slightly breaks markdown rendering, so I'd appreciate any ideas on how best to handle it.