Water pressure problem - plumber tapped into kitchen hot/cold water line to add bathroom sink on other side of wall

I had a bathroom sink added to opposite side of kitchen where there’s a sink/dishwasher. I think contractor hired a plumber who is unlicensed. He insists the guy is licensed but I’ve had too many problems so far to believe that this guy is trained right.

First we had copper line leak that the plumber put in and now there’s no pressure in kitchen sink. the contractor insists the guy didn’t share the hot/cold water line but i am seeing it for myself and the plumber tapped into the cold/hot water on the kitchen wall – tapping into it with T-copper line to add a bathroom sink on the other side.

Is this why i have no pressure on my kitchen sink now? Is that even to code to add a sink in bathroom with same hot/cold water lines?

Note: photo shown is on new bathroom side where sink will go (other side of wall is current kitchen sink/dishwasher)