Typing doesn't work on Android 14 with predictive text enabled

I've tried with Brave, Chrome, Firefox, and Tor Browser, and have tried Google keyboard, Samsung keyboard, and Hacker's Keyboard. When I type, the letters are displayed, but when I hit enter, they disappear and it's as though they were never typed. If I type more characters, all the characters I've typed up to that point appear again.

With Hacker's keyboard, I can hit e.g. ctrl-r for reverse lookup in the history and that triggers the prompt, but I can't actually look anything up in the history because the letters aren't getting through. Tab completion works. Numbers work. Letters don't. I suspect it has to do with autocorrect trying to hang onto the word being typed.

It might conceivably be a Samsung issue; when I find another device, I'll update the ticket.

Ah! It's all due to the predictive text setting. When I turn that off on the various keyboards, it works fine.