Is your suggestion to self host your email or not use email? I’m not sure why you couldn’t find a company that you do trust, and proton seems to be one of the most likely candidates.
If you would like a more technical explanation search for CG-NAT. It allows ISP’s to share a single static public facing IP with several customers at once.
If you had a true static IP that never changed you’ve only see results about torrents downloaded using your router.
I suppose that’s a fair point, although I thought they didn’t have access to your data in terms of email content. I agree with the point about not putting all your eggs in one basket but I’d seriously consider them for email only.