Instant analysis of 49ers’ 28-18 loss to Chiefs in Super Bowl rematch

SANTA CLARA — Wide receiver Brandon Aiyuk sustained what the 49ers believe is a season-ending knee injury Sunday, compounding their sorrowful feelings after being dealt a 28-18 loss to the two-time defending champion Kansas City Chiefs.

“No way to sugarcoat that: We got our (butt) kicked today,” coach Kyle Shanahan said.

While Patrick Mahomes made timely plays against the 49ers’ defense similar to his two Super Bowl wins over them, counterpart Brock Purdy had three passes intercepted...