I've been having this issue for a while now, across multiple computers, where Firefox flags random words as incorrect. I usually notice it happen when it's a newer word, like Scalability for example, but I brush it off since it's not too common. I've been increasingly noticing that it happens to words that are variants of the root word, and I just saw it happen again with Amongst

I know it's set to the correct dictionary of Canadian English, since colour isn't underlined but color is, yet I'm at a loss trying to figure out what sort of Canadian English dictionary could possibly not include words like amongst.

I'm sure there's a ton more than I see these days too, since I've been clicking "Add to Dictionary" for years now after Googling to confirm I'm being gaslit by autocorrect. Who knows how many words are self-additions and not natively recognized (and would you look at that, "natively" is not a word either apparently!)

It's some setting I must have screwed with that's causing it, right? How do I fix this?

Thank you so much! Just updated my browser now, and it's back to normal

I was honestly so freaked out because Firefox is one of the few good products I have faith in still, and was worried it was a design choice somehow

UPDATE: I ran Mozregression to see if I could pinpoint the time that this change was made, and it looks like something between August 28th and August 29th builds was when it occurred.

I'm unsure of what to do here. I went to the link it gave but I don't think any help is there.

Should I revert to August 28th Nightly while I wait for this to be fixed? Or is this just how the design is now?

Here is a picture that better illustrates the change