Install and reinstall apps from the App Store.

I wouldn't trust one of these as far as I could spit it. The trouble with Googling for 'best mac antivirus' is that due to some rather dodgy SEO techniques, many of the top results, if you look closely enough, are recommending their own antivirus, & the only other places that particular one is ever mentioned is on other sites using the same SEO techniques… so it all gets a bit cyclical. Never have two active scan/live antivirus solutions on one machine - they can fight. The free, non-interactive version doesn't clash with any other installed anti-virus. I still do have Malwarebytes on here & do occasionally run it. That's usually my tipping point - when ads to buy a freeware version get in the way or even a paid antivirus starts to feel like it's weighing the machine down. Personally, I recently settled on Avira & it hasn't yet irritated me sufficiently to remove it again. They all have a tendency to rise & fall over time, so you really want one that tends to always stay near the top. So, based on that, I'd look at what is listed on AV-TEST & pick something that does well, not only on the latest report, but also going back in history. When Malwarebytes was listed on there a few years ago it scored so badly that one can only imagine they didn't want to keep paying for such damning evidence. There's nothing wrong with it, but if you look at AV-TEST (which is about the closest thing to an actual official authority on which antivirus is 'best') you'll see it's not even listed.

Everyone always recommends Malwarebytes… however the free version will not actively scan, so you're left with remembering to run a scan.

Macos malwarebytes