When teleporting, it often happens that you arrive looking straight up into the sky.

Homes & Warps are also always set on the cross-point of 4 blocks. I don't know anything about coding but it looks like the decimals of the coordinates are not saved. Setting a warp/home on a slab or similar will then teleport you into the slab on arrival (decimals of y-coordinate not saved).

I don't know anything about coding but it looks like the decimals of the coordinates are not saved.

The reason for this is that an integer (full numbers) is smaller than a double (e.g. 0.5). For this reason, you are always teleported to a full block. I've considered adding 0.5 to each, to put you on top of slabs and in the center of a block, but never implemented this.

As for looking at the sky, this seems to be a bug in vanilla where if you don't provide the looking direction, it won't keep the looking direction.