Streaking like you have a slightly bent blade or bearings out in spindle or belt slipping if your looking at the pic you posted be on the left side of the pic.
It is streaking because it is cutting grass that is over knee deep and really really thick. It is cutting that mess in one pass.
It is getting that effect because it has no where for the trimmings to go and on a velocity deck that is saying a mount full.
We used to run Kubota mowers before we went to Scags. It would have taken 4 passes to get that mess cut down that slick. The blades were fine. They were not bent.
The other lines you are seeing is because of rough ground.