The Symantec software could very well be causing problems and I would recommend uninstalling it since such software is not needed on a Mac, but I realize you don't have that option.
I've seen a lot of users running Cisco Anyconnect seemingly without too much problem. I would consider Symantec more likely to be the culprit if any third party software is causing the problem, but of course the Cisco software is entwined into the lower levels of macOS as well.
Besides, in this case I don't think Symantec or Cisco is the source of the problems since I've seen those error logs on many EtreCheck reports for the 2019 models where people did not have any troublesome apps installed.
Unfortunately the only way to separate out hardware & software issues is by testing the computer with a clean install of macOS without any third party apps installed and without restoring from a backup. This clean install test could be performed by installing & booting macOS from an external USB3 SSD. It is not as definitive as a clean install on the internal SSD since you won't be using the internal SSD when booted from the external drive, but if the clean install of the external drive has the same issues, then you know you have a hardware issue. In the case of a 2018-2020 Intel Mac with T2 security chip, a firmware "Restore" is the best way of performing the test since besides a clean install it also resets the T2 security chip and firmware. You can try a "Revive" which will reset the T2 chip & firmware....it is not supposed to affect the data, but make sure to have a good backup first just in case.
I doubt it has anything to do with 13.3.1(a) since I've seen these error logs posted by so many other users since 2020. The few users who actually followed up later confirmed a Logic Board replacement had been required to solve their reported issue (all involved the same type of logged errors as in your report).
I understand the intermittent nature of the crashes. I can see from the EtreCheck report that it seems like once one crash has occurs that it occurs numerous times in a day or two. Intermittent issues are always the hardest to troubleshoot since you can never be 100% certain when you've actually fixed the problem and it takes lots of testing as well. I can definitely tell you we've had more Logic Boards replaced for our organization's 2018+ T2 Apple Intel models than any other earlier model Macs....and not just the laptops, but iMacs and Mac Minis as well...not necessarily for the exact issue as your laptop. We have a lot more of the 2016-2017 models than we do of the 2018-2020 models, but it is the 2018-2019 models where we have to have the Logic Boards replaced which is very telling in my opinion.
Personally, if the laptop is not still covered by a part/repair warranty, then I would recommend not spending any more money on it and get another laptop. Unfortunately I don't know how well the Apple Silicon Macs are in comparison as our organization does not have enough of them deployed yet, nor have we used them long enough to gain any perspective. It did take a couple of years before we started seeing our 2019 models start to fail. Don't lose out on that 90 day part/repair warranty if you are still within that period from the previous repair.