I guess its just a bug where he's glitched into the trees due to the latency issues. If its something else other than what I interpretted then provide us more proofs so that we can look deeper into it. However, it is not a game breaking issue provided the game is a bit laggy atm so don't fret...
https://docs.google.com/spreadsheets/d/1t5RDg9_fbYTkWpdfQRt_MWcfHWPExOwJjACaED9emYM/edit?usp=sharing
Use this link to know the pokemon coordinates, it contains various other information that would be helpful.
a shiny pokemon can spawn in any where at any given time. There is no common places for shinies to spawn. You can grind for 1 in any snom tile you like. The chances of a shiny spawning is 1/8192.
The link below would be helpful...