So, first overnight experiment after changing ProtonVPN app to openvpn, rather than Wireguard. I never woke up to a disconnected VPN, like I have in the last week.
I wonder what it is about "overnight" that causes the Wireguard connection to fail. Maybe it's not "overnight" as such, but if the screen isn't unlocked for X hours, or something like that. With GrapheneOS, I'd imagine people using always-on VPNs is common, but I'm not hearing any widespread issues about this. I'm thinking maybe it's a bespoke config or app we have installed that's causing the issue.
Other than a standard Pixel 7 Pro, my setup is pretty standard. I've no additional profiles or weird configs. One thing is my phone always charges overnight, and very rarely during the day. Could it be the charging that's causing this? Just thinking out loud!