- Changing the password of your Google account was not necessary. That you did it, doesn’t make any difference, as it was not endagered by the breach. Changing the Google password will have no consequence in Plex – in particular it won’t sign out your Plex devices from your Plex account.
- Your Plex account is still endangered until you change the password of your Plex account. Yes, you do have a Plex password, even if you lately only used Google to log into your Plex account. Doing so will also log out all of your devices, if you tick the checkbox (which you should definitely do).
You can do so right here: https://app.plex.tv/desktop/#!/settings/account – if you remember your Plex password. Otherwise you must go with the “Reset password” procedure as described in the Email. - You need to differentiate between the 2FA codes of your Plex account and the 2FA codes of your Google account. Which to use is depending on how you log into Plex. Either you use “Login with Google”, or you use your email/Plex-username.
After changing the password, you need to re-claim your server
This script might be of use: Server credential reset utility for Linux-based platforms
