I am trying to read the events based on the information published by the media, which cannot be completely trusted, since it will always belong to one of the parties to the conflict.
There is no big disagreement between the sides as to what territory is under their control. You can overlay the map from e.g. Deep State (pro-Ukrainian) over the maps from pro-Russian sources (e.g. Rybar) and it will be very similar.
Unfortunately, Ukraine does not have an air defense system,
False.
and its forces on the ground lack sufficient support and experience.
False, albeit subjective and relative so perhaps some aspects of it can be twisted into "lacking".
Ukrainian forces are generally better trained, have superior reconnaissance, and are better supplied with certain types of modern weapons, although their starting position wasn't too good and Russian forces have huge amounts of soviet equipment and ammunition, not to mentioned their meat grinder strategy. Again, this is all largely confirmed even by pro-Russian sources, if you just look past the official RF MOD "we shot down 300 airplanes of 50 they had" bullshit.
I think you're making the assumption that Ukrainians can't successfully fight back based on false information.