Ravines/canyons don't adapt smoothly to the deepslate transition layer

The ravine is one of the old cave carvers that generates in 1.18. However, when it intersects with the stone/deepslate transitions, it has a weird base where the ravine doesn't adapt smoothly to the transition to deepslate, resulting in an odd ravine base generation that looks like an exposed deepslate layer at the bottom of the ravine.

Step to Reproduce
1. Use seed -25386546
2. Go to 162 8 12

Expected Result
The ravine generates its base properly, even when intersecting with stone/deepslate transition layer.

Observed Result
The ravine doesn't adapt to deepslate transitions, resulting in a weird base at the bottom of the ravine.