Yesterday I noticed the "Upgrade", with a persistent (1) badge on it, in the bottom left corner of the web app, trying to get me to buy some plan with AI features, even after I looked at it. I installed Thunderbird immediately. Never touching Google UI ever again.
Thanks for the recommendation, I went ahead and installed Thunderbird too. Tired of this AI shit being shoved everywhere even if it's unwanted and unhelpful. Done using the Gmail app.