in the nether I went well below the layer -20029284
I ended up stopping at a point, but I could have continued for a long time. at that point, I had a potion effect of resistance, and regeneration but
Please, make that below the layer at most -100 the player gets killed, because the to, it becomes too long!
I hope this bug will be fixed in 1.17

cordially
your fan:

Jeb1400