Screen rotation not working in Ipad mini 6 gen

Swipe down from the top right edge (Wi-Fi/Battery icons...) of the Home screen to see the Control Center, tap the icon with a lock and a circle arrow around it to lock/unlock screen orientation.

Orientation lock  Screen orientation is locked. See Change or lock the screen orientation on iPad.

Rotation failure happened only once. Youtube made rotation slugglish then non-responsive for all apps. Nasty behavior. Normal rotation restored by shutting down Mini, restarting, closing all apps, shutting down again and restarting, in this exact sequence.

What apps are you trying to rotate?

Have you tested it with Notes/Photos apps?