I use Orbot so Bitwarden can connect back to my Strart9 Vaultwarden instance and to run an exposed onion citrine nostr relay on the phone.

I don't have to switch. If you first run orbot as vpn, select single apps to run through it, go to VPN settings, turn it off and then turn on Mullvad as always on and block connections without vpn... orbot will just run in background for selected apps and Mullvad runs like normal.