how to remove the automatic yellow highlight in iOS Notes on my iPhone XS

I think I might have found an (the?) answer.

Because I'd only noticed this on a shared note, I did some digging in those menus. I don't see this menu/icon in non-shared notes so IDK what to do for those.

At the top of my shared note is a Collaborate icon

Tap that, then navigate to Manage shared note - there's a toggle to "Highlight all changes". I turned that off, closed & reopened the note, and all the pesky 'highlights' were gone! It is per device, btw, b/c I had to do the same steps on phone and tablet.

This is the official "share & collaborate on notes" page but it wasn't super clear about the highlight part, more a "stumbled on" thing.

Hope it helps someone else.

In attempting to answer your question, I turned highlighting on in Notes on my iPhone 14. I had never done that before. I eventually got it to stop highlighting (not sure how) and now, as I type in any Note, new or old, the highlighting flickers on and back off, mostly as I complete each word. This issue continues even after restarting the phone.

I've tried everything I can think of I've searched for previous answers and found none that work. I'll keep looking and watching for an answer and will post back here if I find anything.