To me the 4 best examples of where optional casual content (so anything not in the MSQ) difficulty should be are

-DRN
-tower at paradigms breach
-dalriada
-pre nerf orbornne

I’ll give honourable mentions to puppets bunker, edens promise Eternity and E11 (I can’t spell it), CLL and the second loop of thelia’s final boss mechanics (they aren’t interesting but when she does them randomly you can get some mean combos)

There are examples at lower levels but the barebones kits interfere with them being good examples