Why do all fifth generation fighters (J20, F22, SU57) use Trapezoid wings?
Trapezoidal wings have advantages and disadvantages:


Better performance than delta wings at transonic speed
Good stealth performances
Flaps can be easily used.
drag reducing
better Lift/Drag ratio than delta wings 


The problem is that they stall at much lower angles of attack than delta wings.

Edit:this problem is overcome using leading edge,LERX,and/or canards