Proton’s Linux app just sucks and it seems that they’ve made no effort whatsoever to fix this since last year.

This is entirely untrue. The new Linux app, fully rewritten, is currently in beta now:

https://protonvpn.com/support/linux-prerelease/

Let’s not forget that these “technically-correct” but poorly-worded half-truths are what landed them in hot water back when they were forced to log and disclose a user’s IP address for law enforcement back in 2021.

Beating a dead horse, which wasn’t for VPN (VPN under swiss law cannot be compelled to log), but Mail. That is an important difference.