Standing on the hood of a Buick Grand National GNX (after which Lamar named his most recent album, “GNX”), in a sea of dancers, a man clad in black sweats unfurled the Palestinian and Sudanese flags.

NEW ORLEANS — A performer who was part of Kendrick Lamar’s Super Bowl halftime show was detained by security after waving the Sudanese flag and Palestinian flag together with the words “Sudan” and “Gaza” written on them toward the end of the performance, the NFL said.