I remember managing to get this issue solved on my computer. Looks like a QT issue. I may not remember exactly how I fixed it, but try the solutions in this thread and see if it works: https://lmms.io/forum/viewtopic.php?t=34104

In particular run export QT_AUTO_SCREEN_SCALE_FACTOR=0 and then run LMMS from the same terminal.

Also in response to other comments, LMMS is actively being worked on (though updates have been slow) – the last commit on the master branch was from 3 days ago, so that suggests that the project isn’t abandoned but development’s just rolling slowly.

Yeah… Just wow. I disabled pictrs and deleted all its images, which also means all my community images/uploaded images are gone, and it’s more of a hassle to see other people’s images, but in the end I think it’s worth it.

Through caching every image pictrs was also taking up a massive amount of space on my Pi, which I also use for Nextcloud. So that’s another plus!

A bit of reverse image searching reveals this was the original XKCD comic (more specifically, the top middle panel): https://xkcd.com/1269/