When a villager goes through a portal, the villager will keep it's workstation if it is not work hours.

How to reproduce:

Set the time to 1000 (outside normal work hours)

Give a villager a workstation.

Without breaking the workstation push the villager through the portal.

The villager will not have lost it's workstation.

If you try again at any time between 2000 and 8999 (villager work hours) then the villager will lose it's workstation.

My setup to test:

Time set to 1:

Time set to 6000: