Paul is a grandstander and Putin apologist. His motivation is simply to get the attention of the Tucker Carlson crowd and land more Fox News interviews. He does a lot of things for attention. Similar to many politicians. He's just more out there.
As far as the money, Biden's request is something any other President except Trump (and that's primarily because he hates Ukraine and loves Putin) would have done. Blame the system. America always want to be the police and savior of the world. Thats fine because it can prevent bigger threats from occurring, and in this case it can prevent Russia from gaining influence, but sometimes America can get carried away.