Yes that seems to have worked.
I wish I had known to try that much earlier because I tried everything I could possible think of and even experimented with work arounds.
But I’m glad this issue is over.
If you don’t do anything with the forms on that page and try to leave to a different page, you won’t get any popup message.
If you fill out anything at all in any text field then the problem comes up if you try to leave without submitting the form. The message pops up asking if you are sure you want to leave and changes won’t be saved if you do. It happens on Firefox and Chrome for sure but didn’t try other browsers.
The website owner really wants to have this popup removed.