My 15PM started this after updating to 17.1. I reset the phone and started from scratch and it fixed the issue… haven’t updated to 17.1.1 yet, kinda worried this bug might come back. It really makes the phone almost unusable if you’re a fast typer. Not happy with all the bugs in iOS 17!
My 15PM started with the lagging keyboard after updating to 17.1. It was fine until I turned the phone off and when I turned it back on, the text was an odd shape with odd spacing and then that dreaded lagging began! I reset the phone and started from scratch, that fixed it. I haven’t updated to 17.1.1 because I’m afraid it’ll start back. A major PITA to have to reset but worth a shot if you’re up for it. The keyboard lag was more of a pain in the ass to me!