This is the Russia war coming home to roost. They better admit that they are engaged in an actual war, and stop allowing civilian aircraft in areas that are attacked frequently.
Secondary surveillance radar does not depend on tracked aircraft knowing their own position, though.
ADS-B is an augmentation of that, which makes receivers simpler, but ATC generally does not rely on it exclusively (except in some very remote regions), nor on any type of active/cooperative signal or response – if everything else fails (maliciously or accidentally), there's usually primary radar as well.
