Normally my workflow when typing is just to type as fast I can then just go back and correct errors. Unfortunately it seems in my installation of firefox when doing this eventually the red squiggley will just dissapear from under previously typed words as I continue typing. ..As I'm typing here I can see that this doesn't hold true for this textarea box. It must be some specific sites that I'm visiting that cause the problem. The main one that I use where I see the issue is Slack where I do a ton of typing. hmm.. testing further it seems its basically just slack, and when I switch tabs the squiggley reappears on return and disappears when typing again. Can anyone else that uses slack confirm this? Inspect element shows that slack is nesting a p tag with my text in a couple of divs to create their text area. Two divs has a spellcheck property set to true. Maybe their js is messing with the native spell check? This issue doesn't exist in chromium. I set class=ql-editor property spellcheck to false and now there is no spell check at all. This must be explicitly slack's spell check. Sorry this might have nothing to do with firefox, I'm going to leave this here in case someone else has this issue and report to slack instead.