Although I'm on 80.0.361.5, I've noticed for sometime that spellcheck will randomly stop working in Gmail. I've hesitated to report since I cannot document what causes spellcheck to quit working. Here's a screenshot from a new message with Check Spelling enabled. We should see red squiggly lines under every word. (Please note that spellcheck is working in this dialogue box)
@Watney Thanks for reaching out. We just tested it in our personal Gmail accounts in Chrome and Edge Canary and it seems to be working as intended for us. Please give it a try on the updated Edge Canary and let us know if you're still encountering the same issue!
Fawkes (they/them) Project & Community Manager - Microsoft Edge