Shark Stainstriker caused stiffness

Greetings, everyone.

I have recently purchased a Shark Stainstriker and used it for the first time. If any of you have experience with this product, I would greatly appreciate your insights.

I followed the instructions in the manual, using the detergent and oxy, spraying, scrubbing, and suctioning on my couch's armrest. My couch has a soft, velvet-like texture. After suctioning, I believed I had removed all the water.

However, the armrest became coarse and stiff after drying, losing its softness. It also has small markings, which I assume are from the brushing.

Could you please offer some possible explanations for this, and perhaps suggest ways to restore its softness? Is it possible that some detergent remains?

As a first-time spot cleaner user, I am unsure of the proper procedures. And I'm a little sad cause it is a fairly new couch :(