I have the same problem you all, my version is the last 10.3.7, the darkmode is very attractive but the spell check is very annoying, I have notes in English and Portuguese, and some French and Polish vocabulary lists, all words have some red underline...
So I can't use the windows version anymore, I think it's an easy fix for them.
Now I use the web version, is not that great, but has no spell check.