Currently, OVH doesn't offer portable IPv6. As such, if you are using an APEX/root domain, I cannot give you an IPv6 address that I can move to a different server without requiring DNS changes.
If your DNS provider allows for a CNAME (or ANAME or ALIAS) in root domains. In that case, you may use vip.masto.host for one of those records and remove the A records that point to Masto.host.
I will keep vip.masto.host CNAME with the updated IPv6 addresses. That is the only option to get IPv6 support for instances installed using root domains and hosted in Masto.host.