About 50% of the time (so far exactly every other time over several restarts) I get the default application icons for anything I personally pinned to the task bar. This is a brand-new, fresh install of Windows 10 that I downloaded yesterday with the USB Creator Tool.
I have installed the following programs since Windows install:
Chrome, Firefox, JetBrains Toolbox, Rider, Visual Studio, HexChat, git, office, Greenshot, Slack
I have completed all updates.
I have deleted the iconcache.db
Killing Windows Explorer fixes the issue
Just refreshed itself while I was writing this thread.