Password Protected ProtonMail Bridge
ProntonMail Bridge needs to be protected by password. As anyone who uses the pc, can easily see the mailbox username and password in the bridge. Unless the user remember to logout from the bridge properly each time after used, else the bridge will remember the login credential forever. This is a serious security loophole. Especially for those who share their pc.
I think OP may have been talking about an approach not unlike what Thunderbird does: Thunderbird memorizes the IMAP password for an account in encrypted form, and upon startup you type in a local password to decrypt that IMAP password. The way Proton Bridge works, would be analogous to typing in your IMAP password into Thunderbird every time.
It is protected by a password - the user needs to log in first, using their credentials.
If the device is shared, the user should log out, like from all the other accounts. This is by no means a security issue.
Stephanie Anne commented
has this been sorted out? I hope so as it defeats the purpose of moving to protonmail for extra privacy if not...