no doubts that this was shot at by anti air of some sort. Ukraine has been attacking mainland Russia, using their long range "fixed wing" drone planes. These have like 1200 KM range and are kamikaze meaning they only have one way to travel.
IMO Russia had set up defences in Grozny, or surrounds, and alas, the commercial plane - when deviated for poor visibility, got tracked and attacked by the AA.
Now IDK why this failed, given it's an Embraer and not a Cessna sized plane, but still got hit. Evidence is clear as day even if the Russians say otherwise.
Whilst Russia should claim responsibility for this, it is also in a state of war in which civilian accidents are bound to happen.
This applies for any war state. MH17 was shot down in Ukraine too.