We have a new Federal Police force which is made up from employees from other departments. Where did these departments are getting extra ?  ?

They didn't need as many for their regular operations because there is so much less travel.  Airports don't need as many security screeners, customs agents, etc., when there are fewer passengers because of COVID.

One has to assume that during this redeployment the regular activities of ICE, ATF, DEA, et al are suffering. 

They are just too busy defecating on cars and rubbing their own fresh human poo all over them when everybody sees them do it.

DEAD WRONG. We have preexisting federal law enforcement officers assisting the preexisting agency primarily responsible for protecting federal buildings when local law enforcement is ordered not to do so.