You are right, Manchester United indeed dominated the match but they were lucky because Casemiro scored in the 94th minute
Chelsea should have managed to get 3 points but all disappeared in the final minutes

but yeah 1-1 is fair enough for both teams
who would have thought that minutes are crucial for Casemiro, he is a hero. The game was boring enough without a convincing attack for each other between 80', maybe waiting for a counterattack but using a bad time strategy until McTominay exaggerates to violate Broja. After a penalty, Chelsea should have pulled back all players so don't let Casemiro go roam the penalty area.