[DNSB]

Looking at the error message you received from Google (which is pretty much identical to the error message in @shopsis' in message #3 in this thread):

reply: b'534-5.7.9 Application-specific password required. Learn more at\r\n'
reply: b'534 5.7.9 https://support.google.com/mail/?p=InvalidSecondFactor w13sm14947654qko.20 - gsmtp\r\n'

Have you tried setting an application specific password? The link in the error message indicates that that is required. Follow the link to Sign in with App Passwords in your error log or click on the link in this message.