After some more searching, I found this: https://apple.stackexchange.com/questions/420773/the-process-com-cisco-anyconnect-macos-acsockext-hogs-mac-cpu-but-cannot-be-kill
These running filters also prevent Mail's private loading of email content from working under macOS Monterey 12.1. The only solution I have found so far is to uninstall AnyConnect and reinstall it when I need to use it. What a pain. And so far, no re...