Uninstall Bitdefender and any other anti-virus apps, cleaning apps, and third party security software by following the developer's instructions. These types of apps are not needed on a Mac and usually cause more problems than they solve plus they impact system performance.
One of the Kernel Panics also has "net.sf.tuntaposx.tap" & "net.sf.tuntaposx.tun". I'm not sure what app these are for, but you may want to consider uninstalling the app they are associated with if uninstalling BitDefender does not solve all your problems.
If you still have problems after uninstalling these items, then run EtreCheck again and post the new report here.
You may also want to run the Apple Diagnostics to see if any hardware issues are detected.
Disconnect all external devices in case one of them is causing a problem.