Stop autocorrect changing previous words

To start, I have both autocorrect and predictive text disabled, and use the swipe keyboard. iPhone 12 mini, current iOS, though this problem has existed for years with my XS, 7, and iPad; it just seems to be getting worse.

I find it incredibly frustrating when I’m writing something and I make sure I enter the words I actually want before moving on to the next one, only for the phone to change a previous word.

”I went to the store”

”I”.

“I” + “went” = “I went”. That’s what I intended.

“I” + “went” + “to” = “I want to”.

I then delete “to”, except it deletes both “want” and “to”. I type “went” + “to” and it changes again. Or worse, since I deleted “to”, it now thinks I didn’t want “went” and provides other options. “Went” no longer appears no matter how slowly or carefully I slide it, I have to tap each key. With autocorrect and predictive text off, it does this.

Why would it change a word I typed and left alone?

How do I disable this?