meld 3.21.x still running after getting closed, using 100% CPU

I've noticed that if I close meld right after it gets opened (e.g. from git difftool, it sometimes keeps running and consuming 100% CPU). It seems like some sort of race condition, because you have to close it right after it opens and renders the contents - if you wait a couple seconds, it closes just fine.

I've only ever reproduced on meld 3.21.x (Fedora 33). The previous version (3.20.3) seems to be working fine. I'm using meld mostly from git difftool, not sure if that's relevant.

Attached is a perf profile from the running meld process - it seems to be doing a lot of locking/unlocking, and polling for data on a file descriptor or somethingprofile.txt profile.txt.