Whole of Ancient Depths?

Pretty sure in the first Biome once I’d unlocked the boss all I had to do was get to the gate again without having to do the entire level.

Seems like this isn’t the case on the second biome Ancient Depths.

I unlocked both switches and the boss gate opened. But every time I return I have to do the whole level again completing the 2 switches.

Not really a complaint, just find it odd compared to the first biome.