Tuta has a linux desktop app, and their android app is on fdroid and doesn’t depend on google play services. Plus they use green energy for their servers
I was tired of proton because their linux vpn app is pretty awful, especially if you use iwd instead of networkmanager like me. Plus they don’t even support ipv6. So I was switching to mullvad vpn (which has great linux support and ipv6), and then for the price of just email tuta was cheaper and better on all the things I mentioned without any downsides (to me), so I switched.