I've somehow enabled overtype mode in Slack and I can't get back to insert mode

No, dear readers, as the Internet might have you believe, none of *these* things work on a 2017 Macbook Pro, the kind with the touchbar: - Fn+Enter - Fn+M - Fn+. - Fn+Option+Enter Somehow, someway, when I was pasting some text I ended out getting into overtype mode in Slack and now it's stuck that way. Internet documentation might work if I had an older computer or one with keys that I don't have, but there's nothing I've been able to find that will tell me how to turn off this dratted overtype mode. And it's seriously annoying. Any clue how to turn it off?