Don't pander conspiracies there is zero evidence of an SU-30 going down or even being in the emodiate area. The Mig-21 broke formation and got shot down after going deep into Pakistani controled Kashmir, there was reports that his wingman was another Mig-21 but he returned safely. Both Pakistani and India reports are laughable, both have been caught blatantly lying. The stupidity is kept alive on this forum.
Eye witnesses claimed seeing several parachutes but it was over Pakistan controlled territory. If Pakistan had SU-30 wreckage they would parade it.
One thing is 100% certain, a Mig-21 was shot down and the pilot taken POW. Many reported seeing multiple parachutes but it was over Pakistani controled territory. Make what you will of it, but people claiming it is an SU-30 is not only irrational but doesn't make logical sense nor is it supported by evidence.