Free (Premium) Stash tab is remove only

When you create a Character on the ps5, you're given all stash tabs (plus a premium) for free.

You can access the non-premium on PC (as they are not purchased, free)

But the free (premium one) is counted as if it was purchased (remove only) on the PS5. It is/was a free tab and as such... should not be restricted to PC/PS5. Should be useable from both.

If it was purchased on a PS5, I would understand it being locked.

With that said, what happens if I upgrade them (free tabs)? Does it make them locked to PS5/PC?