I work in microbiology and only recently learned it's actually a fungus.
Disclaimer: I'm sure I've learned about it in the parasitology classes I've had but that was 15 years ago and since then I've been in bacteriology and sequencing.
It got that name because the welts look like a worm in a circle under the skin. It looks like a raised red ring about 2-3cm in diameter that is usually pretty painful and itchy.
They made this big to-do just a couple of years ago about renaming monkeypox because they didn't want to offend men who have sex with men, and now here we are with some fungal infection still being called "ringworm".
There's no worm! No parasite of any kind. Really ridiculous name. Also, it can be caused by a number of different fungi, so it's not even really all the same infection.
I believe mpox was, sadly, renamed because racists and their use of “monkey”. I think that was more the issue over men who have sex with men. “Ringworm” isn’t a slur though lol