All System Extensions missing from Preferences pane

We can likely tell what to remove from affected Macs using Etrecheck...

EtreCheck is a FREE simple little diagnostic tool to display the important details of your system configuration and allow you to copy that information to the Clipboard. It is meant to be used with Apple Support Communities to help people help you with your Mac. It will not display any personal info.

https://www.etrecheck.com/

Pastebin is a good place to paste the whole report if you capture the URL while there…

https://pastebin.com/

Whew, they've changed pastebin & made it harder, but after pasting in, click Create new paste button, then Embed button, then copy the URL...

<script src="https://pastebin.com/embed_js/KuvnghqA"></script>

The important part of the above is...

https://pastebin.com/embed_js/KuvnghqA

Workable but harder for me to work with...the Note tool on the bottom of this editor's toolbar, as shown in the image, to copy and paste the output from EtreCheck. In a Reply before you click post, look for this to add longer texts...

Quite perplexing, even moreso from afar!?

See if you have unknown Profiles.

To remove a configuration profile in macOS:

1. From the Apple menu, select System Preferences....
2. From the View menu in System Preferences, select Profiles.Note:
3. Profiles won't be visible until you have at least one profile installed.
4. Select the profile you want to remove, and then press the - (minus) button. Click Remove to remove the profile.

Yes, since you've already tried reinstalling the OS over the what's currently on the drive and standard OS functions still don't work, then I'm afraid you're at an erase and rebuild.

To stress this part again: If you don't have a backup, make absolutely sure to create one before doing anything else. You'll need some way to restore your email and other personal data.

When you have a backup in place, restart the Mac and hold down the Command+R keys to boot to the hidden recovery partition. From there you can run Disk Utility to erase the drive, then reinstall the OS.

If you have a Time Machine backup that was made BEFORE installing Kaspersky, you can merge it in. Personally, I never use TM so I can't tell you exactly how that works.

When you do have your Mac in a functional state, never, never, ever install such garbage again. There are no Mac viruses. No AV software will do anything to stop you from installing the many Trojans out there. If you get any Windows malware as an email attachment or download, they can't do anything to the Mac OS. In short, AV software is useless.

Clone backup your system before any diagnostics are done.

Etrecheck is really good at isolating LaunchDaemons that don't belong.

Zeobit, MacPaw software should be removed in safe mode with the shift key using Devon Technologies EasyFind

Show in Finder on each suspicious file.

And anything else you don't recognize from your Etrecheck report.

No cleaner software should be installed, no keeper software.

They are all attempts at luring unsuspecting new Mac users into installing software that is at best overzealous in its protection, at worse, it creates a headache for launching applications and slowness.

Once Malwarebytes is run, and Avast, you should not need Kaspersky or any other virus cleaner software except when machines start misbehaving again. The best protection is training every team member to learn signs of social engineering before they touch a computer.

I offer paid consultation through my profile.

Well, it proves your IT people know absolutely nothing about Macs.

For a system now this screwed up, I'd first make a full backup of what you have, then reinstall the OS without erasing the drive. Hopefully, it will fix what the Kaspersky install botched so you don't have to go as far as erasing the drive and setting it up again from scratch.

We have more than 100 machines impacted :-(

Ouch! If this is a third party IT group you're paying to manage your equipment, they should be fixing the mess they created for free. Then find a competent IT service to replace them.

SIP will still be disabled until you re-enable it (csrutil enable). Or, the one line for SIP you can run from the desktop, (csrutil clear). The latter removes any changes you've made to SIP's settings and puts them back to the defaults. SIP will be back on when you restart.

I did a full drive search of both Catalina and Big Sur. There is no such .plist item.

So, the question is - what put it there to begin with? Kaspersky?

I was going to download the installer for Kaspersky and use a utility on it that shows you where all of a package installer files go. But, all you get from Kaspersky is a stub item that downloads and installs the app from their servers on the fly. No way was I going to do that to my Mac.

There's also nothing on the web that's an exact match for that .plist name.

To further add on to @Kurt Lang point of AV software - good article worth making the IT person read