Virtualmin messing up DNS of alias domains

SYSTEM INFORMATION
OS type and version CentOS Stream 8
Webmin version 2.001
Virtualmin version 7.3 Pro
Related packages Bind

Lately I have observed that domains that are added as an “alias” of my main domain are having their DNS entries modified with incorrect information. My main problem is that since we use an external filtering service for email the MX records are incorrect.

Here is a detailed explanation:

Domain1 (Main Domain)
Domain2 (alias to Domain 1)
Domain3 (alias to domain 1)
Domain4 (alias to Domain 1)

I usually only havo to make modifications to the DNS of Domain1 and all other alias domains will replicate the changes. Except that for some reason CNAME entries get weird. I would expect CNAME records to be exactly the same in all domains. I can see that CNAME entries in DOMAIN3 for example have DOMAIN2 as the CNAME target instead of DOMAIN1. Same for MX records. Since my filtering provider gives me a target of DOMAIN1.theircompany.com for all domains and their aliases, the MX records on DOMAIN3 are set to DOMAIN2.theircompany.com which prevents that domain from receiving any email.

This is a problem I have only seen in the past few months so I guess it was introduced in a recent version of Virtualmin. I have to solve it by manually modifying the hosts files for the domain. The problem is that modifications made to DOMAIN1 in Virtualmin will overrride the files again. How can this be fixed?