This bug only affects you if you got domain validation (eg by dns-01) but didn't immediately issue a certificate.

Letsencrypt validates the domain ownership for 30 days, so the bug allows you to issue a certificate within that window, even if you added a CAA record after validation that says "don't allow issue by letsencrypt, or only allow issue by MyCA.example.com".

But if you have everything automated, you're checking for renewal and issuing every day and probably validating as part of that, so unlikely to encounter the bug, unless you validate in one step and then sometime 8h+ later, issue a certificate.