OpenBoard is FOSS and doesn't track you. You can disable the user dictionary if you consider that tracking.
I know how to proofread. The vast majority of the time it chooses the word I meant, and it's trivial to fix the mistakes. Without it, I can't get through two words without a typo, as evidenced by my original comment.
Caring that someone else requires autocorrect to be an effective communicator and calling their usage of it "very strange" is dick thing to say.