I've noticed since updating to 1.17 that you can no longer move stacked shulker boxes around inventories without them unstacking unless you're shift clicking. This is kind of annoying. Would be cool if you could add pre 1.17 behaviour as an optional feature.

Stackable shulker box thing is a fabric-carpet feature, so I'll suggest you to make a suggestion there

Fair, I'll go ahead and suggest that there. No clue why I didn't think of that myself.