Cloudflare gives me captchahell with infinite "click on fire hydrants or vans or bicycles or stoplights".
Amazon just pretends to "site error".
Numerous sites like Tiktok, JLwaters, my state's data portal, and others just give me a 403 forbidden.
Other sites just load a <html></html> blank document on my VPN.
And Proton is actually kind of hard to get port forwarding turned on. You can do it by adding a suffix to the OpenVPN name, or by generating a wireguard with port forwarding on.
But again, I don't think it's anything to do with port forwarding per se. The current web demands deanonymization. And naturally "abuse" is blamed, even when attached to legit accounts with legit historical purchases etc.