Losing health when climbing down stairs/block/slab

Since new update, many things have improved but my friend and I have noticed a new bug in our realm: we lose health whenever climbing down stairs/block/slab.

Stairs are the worst because we have long stairs that reach the bedrock and we die almost every time (even with full diamond armor). To go around this, we have been going down stairs with our horses, but we still lose some health, though not enough to kill us or the horse. The wierdest thing about this bug is that it doesn't occur at the spawn point where we also have bedrock-reaching stairs. It happens at our city quite far away from the spawn point (snow biome).

At first, I thought it had to do with the material, so we tried different types of stairs (stone bricks and spruce). Then we tried turning our stairs into slab-stairs. Still, that didn't solve the problem. Then we thought, it had to do with the mobs in the tunnels around our staircase. So we cleared them all, and torched the whole tunnel network. Again, we still die climbing down our stairs.

Also, you may want to note that there's always a delay of a few seconds before we die. First, we lose like 3-4 hearts, then after a few seconds, we die. I think I've said it all. Thanks for looking into this!