RedHenry
Could you maybe describe the error/problem occurring in more detail? For me it's not clear what you're exactly talking about. Giving more informations probably lead to a more efficient help here.
You could for example give informations about:
- where/how does GrapheneOS "say" your email doesn't exist?
- which phone, which software versions, etc. are you using?
- was there perhaps an event before "phone suddenly says" that you remember what helps to understand the cause?
Since the problem is only vaguely described, let's try: Are you perhaps logged out of your Proton account or is there a problem with your login to Proton as described by raccoondad .
(Side note: Proton VPN has received an update yesterday, Proton Mail last update is from October 2023.)