Be sure to not include password when setting up the account. And be sure that cookies are accepted, as defined in settings>privacy&security. Gmail does not use APP passwords.

I have read on several forums about trying to set an APP password and use this during the login process, it seems that someone has solved this way. In any case it was just a test, it doesn't work in any way.

Cookies are active, I also tried adding an exception for "https://accounts.google.com", but nothing.

Are you saying you get an error during setup if password is omitted?

Not sure what you mean.

I insert - "Name and surname" - "Email address" - "Password" (I tried both to enter the password of my Gmail account, and the one created by my Gmail account in APP passowrd)

The Imap and Smtp configuration is done automatically, the google popup opens, the notification arrives on the phone, I accept the notification on the phone, I confirm on the popup on the desktop, and Thunderbird shows that error.

I am suggesting to enter NO password during setup.

I haven't tried this method yet, unfortunately it doesn't work

the problem is solved, apparently somehow XAMPP creates problems, I closed the program and managed to configure gmail accounts on thunderbird