This morning, Thunderbird started asking me to log into my Gmail account out of the blue. After pressing Next, the same page opened in Firefox, and after selecting my account there and pressing Next, I simply got a generic page with the title "500. That's an error" and a simple text asking me to try again later. No matter what I do, even trying different browsers, the result is the same. I can access Gmail through Firefox without problem, and my Gmail account worked just fine yesterday with Thunderbird. I have not changed Thunderbird's configuration for months, and OAuth2 authentication has worked without problem since I activated it back in 2022. What can I do?