Some mineshaft corridors don't have support in the walls

I was testing this world and I noticed something strange in the mineshafts, some corridors of them have no support...

The world was created in 21w17a, without datapacks included.

Seed: 5872862164234670138
Position 1: -144 23 539
Position 2: -122 23 527
Position 3: -96 20 570