The Bug:

Functions that teleport entities will refer to their initial location when executing commands after the teleportation.

How to Reproduce:

1. Create a function with these two commands:

   tp @s ~4 ~ ~
   setblock ~ ~-1 ~ red_concrete
   

2. Use this function in the world.
   → You would expect for this function to move you, then set a concrete block under your new location, but the concrete block is under where you were before you were teleported.