You probably don't have a premium account; you have the whatever they call the new premium accounts. The premium accounts are legacy and don't get new features, so you just have those features and don't get advertised them.
There are also the thinly veiled 'news' emails that show up with special CSS flair in your inbox- but it's not news, it just them trying to upsell you stuff and get you hyped about [Latest Product].
It connects to proprietary services which makes it not an option. The same situation for Tuta Mail. We can talk after they publish their server source code. Proton is also not an option for the same reasons.
Your point is valid but both are not the same, Proton has more to offer and is now a non-profit which you can't say that about Tutao GmbH (the company behind Tuta/Tutanota)
Our team created a custom notification solution and managed to implement it in an energy-efficient way, an alternative to Google’s FCM that lets us fully bypass Google’s infrastructure.
FFS, it's a calendar. It has no business connecting anywhere.
Its a similar problem with Proton for me. Proton doesn't even let you sync to 3rd party cal app on the free tier.
If you're going to paywall basic functionality, that just prevents me from trying it for a while and eventually become so tied to it, it's difficult to break free. Google had the right plan from the get-go.
IMO they're both good options. Afaik, Tuta has an open source backend, unlike Proton. However, Proton has had great recent independent security audits, and court orders against them have shown how little information they keep.
Proton offers more features and services, which also makes it a bit more expensive. I've used and like both, but right now I have a Proton Unlimited subscription because I like their drive, vpn, and password manager.