I have a 2015 (bought it new; currently 51,000) and had the hood up the other day and noticed the same thing - I believe from the front of the engine (front leftish). As far as I've seen everything is fine and there are no issues; seems like I've heard it before; but can't remember for sure.
My 2015 wrx has had that loud ticking noise since I bought it brand new off the lot. I think it's the direct injection injectors or high pressure prump. Direct injection motors always seem to have that loud ticking. I wouldn't worry about it had mine for over 40k miles and running strong.