I voted this because I saw it in initial streams of the game in various city locations.
It may be a specific tree type used in cities that has the wrong scale, probably a very quick and easy fix unless it is one of those nightmare bugs with seemingly unrelated code that somehow causes it .
EDIT
Having seen this screenshot I have anew theory.
Given it seems to happen in cities and is all types of trees then it seems to be the AI autogen mistaking a building for a tree or drawing the tree to the size of a tall building.
Perhaps the title of the thread could be changed as this seems to be a global issue as you say and stating Vancouver specifically in the title might suggest it is only a localised bug,