While it might be connected to the war, note that "Another one of our Migs crashed" is more frequent in the news than "Voyager leaves the solar system".
One is none, two is coincidence, three is enemy action, let's not get ahead of things here. Older MIGs are not the most reliable craft and single engine jets are always at risk of some kind of mishap. These planes are now flying many more sorties than they have made in years.
A 50+ year old museum piece MIG, and the SAR chopper was asked to return due to bad icing conditions before it was lost. It's almost certain that this was just a freak accident.