The changelog for 23w04a states:

• Netherite Upgrade Smithing Templates can be found randomly in all Bastion Remnant chests, and there is a guarantee of 2 in every Treasure Room Bastion Remnant

However, this is only true when 2 Bastion treasure chests are present, and sometimes there are fewer. In the treasure chests that do spawn, there is a guarantee of 1 Netherite Upgrade Smithing Template per chest. Credit to RetroDestroyer for discovering this.

I am not sure whether the current behaviour is intended, or whether it was intended that you can always find two, so I reported just in case.