Does mutt support oauth yet? If not, this will be the last straw for G Suite from me. I can sort-of understand turning off "less secure" apps in consumer Gmail, but forcing "security" requirements for private, paid enterprise accounts is ludicrous. Time to find a provider which treats me as a grown-up capable of independent security risk judgement.
that said, why they insist on turning it off, rather than just use ASPs, is a bit unfriendly. but it's definitely not because they are treating you as a child.