A while ago, I modified this very script so it adds a coloured outline and a tag to indicate what the unveiled image used to be. More recently, I updated to works on all feeds, including user activity page.
I didn't make a fork before, and I just downloaded the script and modified it, and uploaded it to the a channel on KYM Discord.
I'll make a fork, push the changes, then post a GitHub link, then submit a pull request here soon.