Interesting. Do these any of these bugs (Release notes for ArcGIS Pro 2.4—ArcGIS Pro | Documentation) apply to your situation?:
Unable to make a connection from ArcGIS Desktop using database authentication login if the password contains the } character.
Currently borrowed ArcGIS Pro extensions do not allow other login accounts to use the extensions when disconnected from the License Manager.
If that doesn't work, I would see if it's possible to change my Google settings, like Content or Privacy sections (Settings > Show Advanced Settings)
I do not have any special characters in my password and don not use a License Manager. My setup is a ArcGIS for Personal Use with a AGOL-organization.
I have requested Esri support if they can transform my account to a regular username/password account.
Danny de Groot
Outlook for Android<https://aka.ms/ghei36> downloaden
Esri has been busy with this problem, I have sent them a Fiddler trace of the network traffic. They believe the sign in process is attempting a two facor authentication. I have not enabled this for my Google account and am waiting for them to reply.
Danny de Groot
Esri Technical Support has logged BUG-000127774 Signing into ArcGIS Pro with an ArcGIS Online account that uses Google to sign in fails with the errors "An error has occurred in the script on this page" and "Google couldn't sign you in." We are currently looking into this issue. If you encounter this issue, I encourage that you submit a support ticket so that we can get you attached to this bug.