Trump and Republicans are using Barr's dropping of the case of Flynn as an opportunity to go after Obama and former Obama admin officials (including Biden) for 'unmasking'/targeting Michael Flynn as a means to go Trump.

There isn't really any allegation of actual wrongdoing because there was none hence Trump when asked about the crime Obama committed said 'Everybody knows what crime he committed'

It's the same play they ran in 2016 and the same play they ran during impeachment with Hunter Biden and Burisma. Rand Paul is once again, right out in front.