Sometimes these bad days happen.
The number of shots is misleading, as while we did have some good chances, it wasn't as many as that makes it seem, our xG was about 2, and we scored 1, should have scored a few more perhaps, but it happens. Leeds scoring their only 2 shots is more annoying imo.
Pep did nothing wrong, the fringe players playing together looked odd... expectedly. But they needed minutes. We got away with heavy rotation against Fulham and Leicester, and didn't today, was bound to happen when we rotate that much. Lacking the big creators like KdB and Mahrez, while putting Cancelo out wide hindered making more quality chances.
Of course we should feel upset, but don't let it hang you, move on from it, Dortmund and Chelsea were the priorities, there was a reason for the rotation.