As title says. If one sets up a custom panorama to replace the built-in TU69 panorama in a resource pack, it gets ignored by the game and continues to show the TU69 panorama despite there being a replacement provided by the resource pack.

It's a vanilla problem and my mistake in the panorama path, I wrote "/" at the start, that is invalid, but still the texture loads normally, and causes this problem with resource packs.
Whatever, it will be solved in the next version