I've also noticed Gmail spam filter became useless for anything but the most obvious scam/phishing, it seems any mass marketing gets thru as long as they follow some "best practices".

I've been using iCloud email with a custom domain for a while, and it has been super conveninent, stable and spam-free. I also trust Apple more than Google in terms of privacy rn. So if you already pay for iCloud, give it a try.

I'm on the other end, Gmail sends to spam all sorts of legit things. Including mails from the "Google Assistant Privacy Litigation Settlement", conveniently enough.