It appears that Camerfirma was revoked from Mozilla Firefox 88:
As many of you have pointed out, there do not appear to be remediation
actions that Camerfirma can take at this time to sufficiently reduce
the risk of continuing to keep the Websites trust bit enabled for the
Camerfirma root certificates. Note that Camerfirma has indicated to us
that they are ...
My testing showed that the serial numbers seem to be used to uniquely identify the certificates that are revoked. Therefore, if two certificates are using the same serial numbers, revoking one will cause the other to be "revoked", too, so the other certificate won't be able to authenticate the user.
Therefore, it's true that the serial numbers of ...