Today’s (12-11-21) Blue Origin New Shepard crew landing looked to be at full 15mph with no evidence of retro rockets firing or slowing of the capsule. Did they fire?
The live stream shows clear evidence of the retro rockets firing (they don't fire for long, nor do they have to):
Notably, see the dust cloud form before there is slack in the parachute lines. The slack in the parachute lines indicates when the capsule hits the ground.
The slowdown can also be seen in the on screen telemetry, though take these numbers with a grain of latency.