2 different parts of a chunk (for the mob cap)

idea:

making two parts of a chunk for the sake of the mob cap.

Why this should be added:

We have all seen someone build a farm and they have to fill in all the caves around it to make sure mobs don't take up the mob cap. This was more of an optimization thing since pre 1.18 there weren't THAT many caves for mobs to spawn in,

WELL, not only is the Minecraft world WAY more hollow, but it has also been made way bigger, with the addition of the negative Y coordinates (and also the fact that the surface was made higher). Caves are like the perfect place for mobs to spawn so the mob limit can get maxed out really easily with a very high percentage of mobs underground. Players resort to using TNT dupers or other methods of mining to get to bedrock just so the mob cap isn't taken up by those underground mobs.

My proposed solution:

Make two parts of a chunk (purely for mob cap purposes), the chunks will behave like they are the same chunk, generate like one chunk etc. but they will have a separate mob cap. The first chunk will end around 20 blocks under the normal surface (y=50~) and the second will begin below that. there could also be a setting when you make the world to change that number but by default it would be y=50.

DISCLAIMER: this idea may not be (and probably isn't tbh) perfect, but i believe the problem is real. Ty for reading and have a good day! idk if i should put this as caves&cliffs or mobs section.