I had a question about that a while ago: https://forum.cloudron.io/topic/12503/what-will-happen-when-i-enable-ipv6-on-cloudron-when-some-domains-don-t-support-it/2?_=1733313066534
@girish suggested this:
If you change the provider of the things you don't control to no-op, and make sure A/IPv4 is correct, then it won't crash and just ignore them. Certs should also be renewed (as long as there is no incorrect AAAA record).