Warden can be spawned in peaceful mode

Summary
The Warden can be spawned in peaceful difficulty, which is not supposed to since the Warden is considered a hostile mob on Java Edition.

How to Reproduce
1. Set your difficulty to peaceful mode.
2. Spawn a Warden.

Observed Result
The Warden could be spawned on peaceful difficulty.

Expected Result
The Warden should not be spawned on peaceful difficulty.

Original Description
So i was playing normaly until i got a lot of lag from the wardens
So i made the difficulty to peacful so it despawn

But still they didn't despawned so i used the kill command
And started to spawn some with spawn eggs and yes
No problems and it spawns in peacful mode

So plz fix this