The general consensus is that treasure vaults are unliked. The limited interactivity with the level doesn't justify having a high reward, however the stage is a "Treasure Vault" and yet hardly lives up to its name.

A fair compromise, to make these stages still a safe break, and yet still have them as rewarding stages, is to add new mini-games to treasure vault stages. Say perhaps 8 different mini-games that are not very dangerous and award a fair amount of crowns.

One game you could have a bouncing money bag that the players have to hit to drop crowns, similar to the Punkin King mechanic. Meanwhile some kleptolisks are respawning, something like that.

Perhaps another you have a spinning low damage bullets going around in a circle, and you have to repeatedly bring a key from one side of the room to the other to unlock treasure chests while some tier 1 respawning polyps are shooting at you.

As a last example, perhaps there's a target shooting mini-game where you and your buddies have to throw pots or shoot bullets at these targets that cause crowns to appear, meanwhile some royal minis spawn on your platform just to annoy you.

Just some fun light hearted games that aren't really that dangerous but they're something to do to justify a higher crown payout.