Kendrick has been having a pop at Drake - for reasons. Drake has tried to sue over the lyrics. Kendrick claims that Drake’s favourite chord is “a minor”. Drake has, uh, a reputation for liking young girls.
TLDR; rapper for the ages calls pop rapper a paedo at half time show in a sport that most of the world don’t watch.
Tldr: Kendrick is song fighting Drake. Kendricks song beat Drake super bad because Kendrick's song won a bunch of awards while calling Drake a pedo. Then Kendrick sang the song during the Superbowl. The most watched sporting event in America. So now a bunch of people have been told Drake is a pedo.