Leclerc's no 2 PU was taken care of after Monaco, it was reported on several media outlets and here as well. It was a minor issue that required an intervention in the factory, couldn't be solved in the garage. There's no chance any team could run on 3 PUs only, that's 33% longer life span than they are designed for
Both Leclerc and Sainz were on target to use 4 PUs and the team took their chance to give Sainz a new PU in Brasil due to poor starting position only