Small numbers of light vehicles entering towns they have not overcome...are then promptly destroyed by irregular Ukrainian forces often with improvised weapons.
Seemingly trying to take large cities without first gaining and controlling ground and surrounding areas.
Lack of attempts to destroy strategic infrastructure at the beginning - e.g. TV/broadcast, communications, bridges, rail, etc - using cruise missiles or whatever.
Unclear objectives - are they really trying to actually take Kiev or just force Ukraine into submission?
Effective use of an air-force is pointless without dealing with the above issues and more.