Content Log error appears "[Structure][error]-[[Jigsaw Structure]] couldn't be constructed, no pool named `minecraft:trial_chambers/chamber/end`" in worlds

In existing worlds and when creating worlds, this content log error can appear:
[Structure][error]-[[Jigsaw Structure]] couldn't be constructed, no pool named `minecraft:trial_chambers/chamber/end`

This can only happen completely in vanilla (no RP/BP), without enabling the Update 1.21 experimental toggle in the world.