Unable to access Security and privacy

Symantec has a device management solution, but they also do antivirus (they are far more known for the latter). Many organizations use Apple's MDM for device management and deploy a separate AV solution like Symantec, Sentinel One, etc. (since Apple doesn't offer one other than macOS itself). You may have uninstalled Symantec AV, but your device is still a managed device.

Generally, users cannot uninstall device management software on their own, devices can only be unenrolled centrally (else, what would be the point of device management?). Even if you wipe the internal drive and reinstall macOS, the device remains managed. If the employer is giving/selling the device to you, they should unenroll it first.

The bottom line is that some form of MDM is operating on your Mac, that's why you cannot access the security settings. If you feel that you need to access them, you need to contact the organization that provided you with the computer.

I thought you might be the same person who e-mailed me about an identical issue. But that person was using an iMac, not MacBook Pro. I have to say though, that was one of the best EtreCheck solutions I've ever seen. In that case, the user had Symantec installed and had also installed some other antivirus tool. But then, they incorrectly uninstall the other tool, which caused the remaining portions to repeatedly crash. That crash caused a cascading crash within the sysextd process that managed Symantec's system extension. I'm very confident that all of this eventually led to System Preferences hanging when trying to display the Security & Privacy tab.

Alas, due to Apple policies, that's all the help I can provide on the topic.

Even if you’re an admin in the machine, if the employer/school is using MDM they can lock out some or all of those preferences.

MDM overview for Apple devices - Apple Support