I recently moved my Google Play apps (specifically WhatsApp) to a separate user on GrapheneOS, and I've noticed a new issue. Usually, I receive a lot of voice and video calls from my family, and WhatsApp uses Phone access to ring. However, since moving the app to another user, my phone rings on the current user when I receive a call, but it doesn't allow me to switch to the user with WhatsApp to answer the call (the user options are greyed out). I have to either wait for the call to end or press the power button to decline it (strangely, this works across users). Only after the call has ended can I switch users and call them back myself.
Receiving calls on one user when logged on another, unable to switch to answer.