I don't see anything in there that looks like it could cause this strange behavior...
1) Are you sure that those contacts are actually added to Contacts, and not just "found by Siri" somewhere?
2) Assuming that they are indeed added, how do they show in Contacts? For example, say you send an e-mail
to me@myserver.com, does it create a contact with this for e-mail and named how?
3) If you do the same, while booted in Safe Mode, do you also have it added to your Contacts?
On a side note, I noticed this in the report:
More than one antivirus app - This computer has multiple antivirus apps installed.
Fortunately, these are not some of the very bad ones, but still: I'd uninstall adguard, and keep MalwareBytes but not always running in the background; only run it manually in case you have some reason to (which should be rarely, if ever).
The kind of malware that exists for the mac is one that requires active user participation.
Using the built-in security and a healthy dose of good sense is what is best.