The original problem is caused by the geo that creates a pole on the edge of the right angle.
Adding the loop cuts but leaving the original bevel geo in place doesn’t resolve the pole. So the angle is tighter but you still have pinching.
What you need to do is have 3 edges for your right angle and ideally resolve the extra edge loops to the next corner quads so they don’t propagate around your model. For your model here it’s not essential but if you had a more complicated shape it would be essential.
Does this make sense? Not at PC so can’t add screenshot but I’m sure Martin or Omar will be able to add more detail.
