None of which I use. Do these additional tools scan (or know/compare) every file the OS touches completely? Otherwise these do not negate the issue.

Personally I really don’t want to send hashes or whatever to Avast of every file I open or download. A scan should be local and local only imo. I’m fine with the default settings of the resident scanner as a trade off of performance vs scrutiny. I’m just aware that exceptions exist that warrent further steps. An ISO is one of those exceptions. I understand not everyone ever downloads ISOs, but I do fairly regularly. And happened to do so yesterday so it came to mind.