Hi everyone, I've been having a problem with my Pixel 7a for a while now.

I don't know if I'm the only one, but during a normal call (excluding messaging application) my Proton VPN tends to cut out and therefore cut internet at the same time and this whether I'm receiving or initiating the call.

Does anyone have any idea why?

Thanks in advance.

Does this happen without VPN?

What instantly springs to my mind that if you only have 3G coverage then you won't be able to access the internet at the same time as placing a normal phone call or at least that is my experience with an old phone.
Also might wasn't to make sure that you have 4G calling (don't know it that's a thing for 5G) turned on assuming there is a switch for this in grapheneOS.
If you don't have 4G calling on then your phone will have to switch to 3G in order to place the call.
If you have WIFI as well as cellular then nothing I've mentioned in this paragraph will matter.

If 3G is not the issue well then i might suggest trying the official wireguard app instead of the proton app and see if the issue persists.