On Pixel 6a with the latest version of GrapheneOS installed, this is what I do and this problem occurs:
- Create a second user profile
- In that user profile, location is disabled and I add PIN.
- I use it to browse things like Gmail, Instagram, etc. (with Proton VPN installed).
- After I am done, I switch back to my main profile by clicking on the user icon in notification panel.
- After going back to main profile, I delete second user profile.
- I turn off Multiple Users.
- Reboot phone.
Upon rebooting, the quick settings get reset to default, all my customizations have disappeared.