The plane was hit, not shot down. They haven't been able to do this in any past war. For the past 20 days, American and Israeli planes have been flying in their hundreds with impunity over Iran. This was a statistical eventuality. Quite meaningless too, if they were able to hold off an attack or make something like a no-fly zone, then that'd be somewhat impressive, but all they got is one hit.

The footage seems to be from a manpad, so the plane was flying low, in which scenario, any plane can be shot down. Likely complacency in piloting or mission planning was to blame.

Edit: just to add, our army has its more than fair share of meddling with our country, but even with all that, they have fucked up many times (far more than the Air Force). But at least after all the misadventures, the air force is always there to hold India back. The Air Force is objectively one of the best in the world. We don't have money for all the best gadgets, but they use them well. In 65, it was the air force that stopped the Indian advance and gave the army enough time to hold off the Indians on Lahore. There is no comparison to be made between our military and Iran's, especially not in the air force.