This is not just an IFF system malfunction.
IMHO this is a command & control breakdown.
Russian air defense in Crimea is getting hammered by upper echelon because of the successful Stormshadow attacks.
Air defense is in a hair-trigger mode...shoot first & sort it out later.
With the A-50s grounded, surface-to-air systems are operating in autonomous mode, complicating command & control.
Ah come on man, it’s the cia/s
Ukraine has also conducted numerous strikes on Crimea's Command, Control and Communications centers over the past few months. In addition to the equipment/infrastructure, consider the human losses in these command center strikes too. Datalink management and understanding the entire battle space isn't a simple job, and taking these people out is significant.