I don't know if it comes across on Mastodon, but it appears to me that the best way to let AI take care of these images is to downscale them first to a resolution that Mastodon likes, give them an AI pass / upscale, downscale 'em again and then post them. I noticed on those Junipr photos that the final result of image 3 on my machine was bad. Spots the AI ignored, weird scan lines were introduced, it was not great. Number 4 was handled quickly and easily by the AI, no noticeable defects like 3.