It’s hilarious that you make assumptions. I use the spacebar trick. I place the cursor in the middle of a word, and then the cursor bounces back to the beginning of the sentence or somewhere else entirely. I’ve never had an issue until iOS 17. Hence, seems like a bug.
Edit: I should add, I could totally be wrong. And it still might be user error. I have no idea. But the cursor bouncing all around is a recent issue I’ve been encountering since my new phone and new iOS.