I've noticed that for a number of websites recently (eg. GMail, Twitter) that all the text I'm entering is getting red squigglies (as if there's a spelling error). I have two dictionaries installed and do have spelling enabled. If I toggle spell-checking off, then the squiggles go away. This has only started happening in the last few days/week. Previously the spell checking would work as expected. I'm running Firefox 87.0 (64-bit) on Windows. (Interestingly the form I'm typing this question in doesn't display the problem)