You were probably right. But I got that from my interactions with one of the AV vendors over a decade ago. Since then, the only AV on my machine is Windows Defender. It's not because I need it or trust it, but rather it cannot be easily removed. I always disable it but it will become active might be after a major update, which was quite annoying.
You can disable with local group policy, in gpedit.msc which is the policy editor. Search for the exact path, it's just 5 clicks away, doesn't come back up.