The Yarkant changes so abruptly, I'm curious what special geological feature is at these straight/meandering-to-braided junctions.
The critical factor that determines whether a stream will meander or braid is bank erodibility. A stream with cohesive banks that are resistant to erosion will form narrow, deep, meandering channels, whereas a stream with highly erodible banks will form wide, shallow channels, inhibiting helical flow and resulting in the formation of braided channels.
Here's near the edge of the Pamir range.
Here's another braided section in the Pamirs, far upstream.
Minimal braiding in the Rockies
Mountainous braided rivers seem rare/mild elsewhere, like here in the Rockies in Missoula.