It's not, actually. Even if some problems look the same at a glance, they often are not. So we prefer separate threads for separate problems. Thus, I've moved your post to a new thread.
You should not include the _acme-challenge label for requesting a certificate for a certain hostname.
Yes, acme.sh defaults to ZeroSSL. See The acme.sh will change default CA to ZeroSSL on August-1st 2021 for more information and how to change this to Let's Encrypt.
Why is there a TXT RR for mirnas.xyz with the value _acme-challenge.mirnas.xyz? That doesn't make any sense.