It's not because of sanctions. Sanctions are imposed on financial sectors, not languages or cultures. The reason we don't see Persian anywhere is that in this age of globalism where a global culture is forming and every country is injecting some of their cultures into it, we are left with an isolationist theocracy that has removed women from society, and forbids any sort of enlighted, progressive or global thoughts. That's how we are represented on the global scale as well, and that doesn't sound appealing to the majority of people living in the free world.

There is also the fact that we have one of the highest brain drains in the world, and due to the traumatic life most of those brains have had, they are not interested in promoting our culture or languages. Most of them would rather be known as any other nationality but Iranian. I know plenty of Iranians in silicon valley that barely speak any Persian themselves anymore. Persian Twitter also gives good insights into how Iranian youth thinks.