What do you mean? Europe has contributed twice as much to Ukraine compared to USA. Yeah, in plain military spending USA has given more, but a war isn’t won with just guns. This has been a strategy that has made sense given USAs military industrial complex, and EUs geographical proximity to Ukraine.

If USA pulls out it’s likely that EU will shift some of its aid over to military. This is already happening: European countries have started setting up arms production within Ukraine which gives Ukraine more guns per dollar spent than what donations of western built weapons does. So don’t think the dollar amount donated tells you everything about the amount of military support given.