Yes, exactly. If you do have AAAA records, Let's Encrypt (not unlike other software and services!) will prefer the AAAA records when doing domain validation fo

Yes, exactly. If you do have AAAA records, Let's Encrypt (not unlike other software and services!) will prefer the AAAA records when doing domain validation for your domain. So if you have a correct A record and an incorrect AAAA record, your domain validation process will fail. You can then "fix" this by deleting the AAAA record, but it isn't a fix in the larger scheme of things, but indeed it makes plenty of users happy right away.