When a work profile is removed - whether by the admin, the user, or an automated compliance action - everything inside the work profile is deleted. Everything outside it is left untouched.
On Android 11+ COPE devices, removing the work profile works the same as BYOD - work data is deleted, personal data survives, and the device transitions to an unmanaged personal device.
On Android 8-10 COPE (legacy WPoFMD), the behaviour was different. Removing the device owner triggered a factory reset, wiping everything. Removing only the work profile while the device owner remained intact left the device in a partially managed state, which most EMMs handled by forcing a full wipe.
On fully managed devices (no work profile), a wipe command or unenrolment triggers a full factory reset. All data on the device is erased. There is no personal/work separation to preserve.
See also: What can my organisation see on my managed device?