Watch both goals carefully.
Goal 1. Shaw is caught square on and immobile between Carvajal and Yamal. He fucks up, Carvajal has a beautiful 1 touch pass that lets Yamal run onto the ball and at Guehi, and Shaw never recovers. Everyone shifts over 1 player, Walker picks up a midfield runner (Olmo). NO ONE picks up Williams, Walker tries to get across for the block but can't. Neither Mainoo or Saka picked up Williams, partly because Mainoo is a bit clueless defensively, but MOSTLY because it all happened so fast.
Goal 2. Olmo picks up the ball in midfield with enough time to turn, face goal, put the kettle on and have a cuppa. Bellingam and Rice are sitting deeper than my cock inside Sydney Sweeny in my dreams, and have no hope of offering pressure. Watch Saka and Cucarella closely at this time. Afro man starts his overlapping run when Ruiz passes to Olmo, Saka is very slow to react. Walker DOES fuck up at this time, because the back 4 start sprinting back, each of the other 3 have a man each, but Walker is caught in about 3 minds, because he has Olmo running at him, and he can see Cucarella us unmarked. Olmo makes a brilliant decision to go direct to Oyarzabal, which eliminates Walker. Had he made the easy pass to Cucarella, Walker would have been able to close down. Oyarzabal makes the perfectly weighted one touch pass and even with his pace, Walker now has buckleys chance.
I think both goals involve a brilliant first touch pass from a Spaniard, and that needs to be recognized. But Shaw is the villain for the first goal by a MILE. And I think Saka is the root cause for the second, as he put Walker in a blender.