if it falls at the move from the first "page" of google authentication to the next then the issue will almost certainly be cookies. Just allow them in Thunderbird.

If the failure occurs after you allow the access then the issue is Thunderbird is not receiving the message on localhost. IP address 127.0.0.1. In this instance you generally get the email from google saying Thunderbird is authorized to access your email, just not a working account in Thunderbird.

Generally these issues arise because other software is monitoring the localhost and consuming messages. Development tools, web hosting applications like Apache and sometimes security software (Antivirus/Firewall) are the usual issue. Although I have seen things like the Proton Bridge also cause issues because it is monitoring the localhost adapter.

I reinstalled the gmail account. Removed all google associated cookies and turned off my antivirus. I am running a standard Win 11 desktop with no development tools or hosting of any kind. https://accounts.google.com/signin/oauth/legacy

opens but is blank and now get "Unable to log in at server. Probably wrong configuration, username or password"

When I try the manual settings everything appears top be correct.

I verified the password is correct by logging directly into my google account Retest says that the setting were found

Are you still seeing this problem?