tiktok routes regionally first, that's by design. your first test batch gets picked from your account signals: sim region, app language, caption language, and whoever engages in the first hours. farsi captions plus iranian early engagement means the algorithm keeps serving iran because it performs there.
the strongest lever you actually control is language. english captions, english on-screen text, english audio if you speak it. skip the vpn tricks, they matter way less than people think.
heads up though, it takes a handful of consistent posts to shift the routing. one video won't flip it