Slime farms?

I’m playing Minecraft and I wanted to make an easy way to get slimes as I need a lot of them, without having to go search a swamp, so I built a little slimefarm.

I went ahead and used Xenoshots design as you can see here https://youtu.be/iRkjZ4Blo4U and also built it on a slime chunk, below y=40, but still, while afking like 30blocks away, no slimes seem to be spawning.

I also lit up every cave I could find around up with torches, but it doesn’t seem to help, the results stay the same.

What else is there to do? On the video the farm is working great, but my farm doesn’t work that well… well it’s doesn’t work at all.