LP stove vented into "outdoor" room ?

Neighbor has LP stove vented out to backyard patio. He's in process of covering the patio with a roof and will be over the vent. He will have partial wall and window enclosures to make it kinda like a room, but won't be like a normal room with walls and windows that are air tight and such, but it will still be like an "outdoor" room. But, the vent will now be in this "room".

So, the big question, will this be a problem?

gas units have very specific vent termination requirements, whats the manual say

basically, yes this could be an issue with venting byproducts like CO, and moisture

Stove install was already in house since it was built ~15 yrs. ago, and he's been in there 7, and no clue where any manual might be...I guess he find the model and google it right, thanks!

^ yeah, or report back here and maybe Bob or i can help further

If it's a 15+ year old unit it was likely setup to operate with class B or dual piping. Agree with venting it to an unobstucted location, sounds like in this instance that will be the roof.
FWIW I would never consider venting to an occupied area, regardless of what code may say in your area.

Tell your friend to consult an expert. Even if the room is not airtight, there could be unintended consequences to this decision.