Hello DziejekDziejek,
Sorry about the pasting error. I may need to issue a new update to fix that. The problem is in your "Software Install" list for OneDrive. The version number trips the spam filters in Apple Support Communities. I do have a check for that but it only applies to kernel extensions. I must have added the software install list since then and forgot to apply that same spam-filter evasion tactic. I'll have to fix this since Office is a popular product. I've seen a couple of similar reports recently.
As for your antivirus issues, I can't disagree with what anyone else here as said. One complication is that although true Mac malware is very rare, annoying adware is quite common. Apple's built-in protection does very little against adware. But then, 3rd party antivirus apps also have very spotty performance against adware too.
I do recommend MalwareBytes for Mac. Unfortunately, it looks like when you were testing MalwareBytes, you still had Sophos installed too. EtreCheck will complain if you have more than one 3rd party antivirus app installed. I added this check recently because I was seeing more and more people having multiple 3rd party antivirus apps installed. I thought that was very risky because they all use the same techniques against the same set of files. But in all honesty, it was just a hypothetical concern. I didn't have any proof - until now. So thanks! 🙂
I don't run any antivirus software myself. There are very few that I have even attempted to test. I have run MalwareBytes and it seems to work as advertised. The current version does include a kernel extension. I was skeptical when that part was added because kernel extensions are very difficult to do properly and often cause problems. I have seen a number of reports here on Apple Support Communities from people having trouble with the MalwareBytes kernel extension. For most people, and from my limited tests, it seems to run fine. I have seen sporadic reports of other 3rd party antivirus tools catching some adware, so they do work. But there is no guarantee they will work against all adware, on all versions of macOS, or in conjunction with any other software, especially other antivirus software.
I think maybe if you try your test again, but do a better job of uninstalling, you might have better results. You can't ever drag any of these files to the trash to uninstall. You must use vendor-provided uninstaller or uninstallation instructions. Never use an "app zapper". Never try to manually delete files in hidden directories by hand.
Don't use EtreCheck to uninstall files either! You can use the "clean up" feature to clean up the mess left behind from previous manual attempts at uninstall or "app zappers". But EtreCheck's own adware or unsigned file removals are only meant for adware and malware. It will break any software you use it with. If you use it with adware, well, that's good, because you want to break it. But don't use EtreCheck to remove any unsigned files unless you are sure they are adware. For example, you have a number of unsigned AVG files. Don't use EtreCheck to remove those. Use the AVG uninstaller if you want to remove them. I won't address the question of why a major antivirus company like AVG would be distributing unsigned software. 🙂
Unfortunately, in most cases, antivirus software is simply designed for Windows. They are tested with Windows and against mostly Windows malware. In the past, when I've been forced to use antivirus for US government work, it has been a challenge. Due to said government work, I was years behind on my OS updates. But even my ancient versions of macOS were unsupported by the #1 Mac antivirus vendor at the time, with their top-of-the-line enterprise endpoint protection product. If they fail to notice Apple's new software releases with all of Apple's hype and spectacle, how are they supposed to notice new releases from malware developers who are trying to attract a lot less attention than Apple?
