Google has disabled POP access in Thunderbird. Specifically they have removed the option to allow "Less Secure Apps" from downloading emails using POP access. They define "Less Secure" as apps requiring only a username and password. Currently (as of June 2022) Thunderbird can not download Gmail emails using POP. Just FYI I will gladly give up Gmail and keep Thunderbird. I believe the only workaround is to have Gmail forward all emails to another, more friendly, email provider until I am able to convert all my contacts. Thanks!