Who is at fault here? Yes, Bethesda for its pricing, but shouldn't Valve point that out for me (and the publisher)? Or is this a bug maybe? Usually buying such a multi package gives you (and me) a cheaper price than both individual products on their own, in addition to their individual special offering.
Not really, because none other packages are affected. Usually a bundle has its own offering, where it adds offering on top of to the individual. An example would be how this works like in this (currently active) bundle, notice the 10%:
https://lemmy.ml/pictrs/image/55a63cbd-6d9c-4545-bb12-7e2b9c1f889a.jpeg