RootCron
I don't now about your chairing theory, if anything the system should go into high power mode where there is no need for apps to conserve resources.
this documents seem to indicate that something like this is happening: https://developer.android.com/training/monitoring-device-state/battery-monitoring

Something that is more interesting to me is the fact that your pixel 7 pro has twice the ram of my 6a,
12 GB ram vs 6GB ram.
I used app manager to check the ram usage of my 6a and after a 40 hours (but it's virtually the same after reboot) of uptime my ram usage looks like this:
Memory 5.78/5.87 GB
Swap 2.8 GB/ 3.22 GB

I wonder what your figures looks since you have twice the amount of ram and only one user profile while I have two active profiles.
I might be hitting the limits of my device (or the android system is just opportunistically filling it up) since I have only 6 GB of RAM but with twice that doubt it could be an issue.

https://github.com/MuntashirAkon/AppManager

    Since the Android 15 release Wireguard appears to crash (or force-close) for me too.
    From what I've seen it might be related to Seedvault backups, at least in my case.

    I haven't tested it yet, but maybe it helps to exclude WireGuard from the Backups:
    System -> Backups -> Status (Last backup: ...) -> 3dot menu top right -> Exclude Apps

      Cypher

      Very interesting you mention Seedvault backups!

      Around the same time my VPN started dropping overnight, I had a notification about Seedvault backups backing up Firefox. This notification was frozen, couldn't be swiped away or expanded in any way. A reboot was the only way to get rid of it. I had to disable Seedvault backups to stop it.

      These two issues are the only semi significant issues I've experienced in years of GrapheneOS use, and seems likely they're related somehow. I'll re-enable the Wireguard option on my ProtonVPN app, and see how it fares overnight with Seedvault disabled.

      I don't know much about Seedvault, but if it runs overnight that'd explain why people are waking up to disconnected VPNs too.

          RootCron
          That is what happened for me too: Seedvault was at "Firefox" right after my WireGuard was disconnected. (I checked the SeedVault notification maybe 2-5 seconds after the VPN disconnection notification appeared.)
          But after a minute or two Seedvault continued with another few apps and finished without errors.

          Maybe WireGuard was stopped by Seedvault and Firefox just happens to be the next app to back up for both of us...? But it feels like too big of a coincidence.

              Can confirm it's Seedvault. I exempted the Mullvad app from the backup and last night my VPN wasn't disconnected.

              Agreed, my ProtonVPN app hasn't disconnected its Wireguard connection overnight since disabling Seedvault.

              Very interesting that about seedvault, I have it set up my self.

              I'm going try see if this exemption helps as well, though I can't be bothered right now as wgtunnel haven't been disconnecting like the official wireguard app and I can't be bother to switch back right now.
              In addition I'm gonna have to check if wgtunnel is excepted from seedvault backups and maybe that's why it's kept alive, though it also a runs a perpetual notification which is bound to help.

                yellow-leaves

                From reading the comments on those issues, only the app's main process is killed. If the VPN tunnel is a separate process, then it continues running.

                Apparently Mullvad recently switched to a single process, which caused more people to notice the issue.

                Wgtunnel probably uses a separate process.

                    Probably9857

                    I see, backing up VPN apps makes little sense anyway so if excluding ones VPN from seedvault resolves this issue then everyone ought to do it.