I don’t think this is a thing. Snipers are fairly common regardless. I play a Psyker almost every day and use Psykinetics Wrath all the time, sometimes as soon as it’s cooled down. Don’t feel like I’ve noticed anything linked to snipers.
Though who knows what the ‘behind-the-scenes’ game logic is. Sometimes I’d swear the game spawns stuff behind me just as soon as I cleared one direction and turned around.
Then you haven’t experienced any alternative. Try 5x missions without Wrath from you or your team.
It’s funny, we can believe in a GameDirector that will spawn immobilizers if we separate for too long. But we don’t believe in Wrath aggroing Snipers behind walls?