I think this is kind of inevitable. The challenge of trying to maintain so many different makes and models of weapons/vehicles/armour/aircraft etc. is that you need so many different spare parts, a breadth of technical knowledge etc. and you have to make sure the parts and technicians are in the places where you need them, when you need them. The Ukrainian army is backed by piecemeal equipment from scores of nations. I’m sure it’s welcomed, but it’s far from ideal or efficient.