Slide to type. This "issue" is at most 6 years old for iOS users.
Turn off slide to type if you do not use it. Slide to type does key resizing logic. This is the direct cause of this issue. Please upvote this comment for visibility.
Please reply if you think I'm wrong. I see this get posted frequently enough I'm actually losing it.
Please refer to https://youtu.be/hksVvXONrIo?si=XD7AKa8gTl85_rJ6&t=72 (timestamp 1:12) to see that slide to type is enabled.
About two years ago, my phone typing suddenly gets extremely bad. Like, from occasional error to about one typo every second sentence. No matter how carefully I type. Hardware didn't change, so it must be me, right?
Let me play with that setting, I hope you are right.