The Deep Dark is much deeper (volume-wise) in Java 22w17a than it is in the latest Bedrock beta/preview.

Example Seed: 5085405352177541826 (Deep Dark Delver's Delight. )

Figure 1 Coordinates: X: 423 Y: 38 Z: 342

Figure 2 Coordinates: X: 270 Y: 57 Z: 125

The Bedrock edition appears to have the Deep Dark clamped somewhere between Y 26 and Y 32, whereas Java is either unclamped or can generate the Deep Dark up to Y 74 when generating under a maximum height mountain (Y 256).

When under a maximum height mountain, seeing Deep Dark generate at such high layers in Java seems like the correct thing to do when you consider the surface is still nearly 200 blocks above.