Druid Covenant

[Ebbingford]

Playing as Britonae, latest patch.
I build the Druid Oak structure, can't remember what it is called, and then upgraded it to Druid Covenant. I have done this twice now in one region and the upgrade has removed the modifiers that the original one gave.
Is this WAD?
Should the new modifier remove the old one?

[Pocus]

Yes, once the base building is built, it will convert randomly to another 4 possibilities for some turns, then will revert to the base building again.

That's nature changes