In testing of W11 (Pro, domain joined), I have found an issue whereby if a user profile folder and associated registry key are deleted (i.e. as you might do with a corrupted profile), the next time the user logs in the taskbar is completely blank, apart from the arrow which reveals the system tray icons. This issue then seems to persist.
Anyone else found this / have a solution? I seem to recall that there was a similar issue which appeared with one of the W10 feature updates a year or two ago, which was fixed by the following feature update.