Looks to me like your spray atomizer was set on squirt rather than on mist. The squirted on cleaner had lots of dwell time and shows in the end, how clean that fabric can actually be. Because the rest of the material is still dirty you see the clean areas where the wetness of the product alone did the cleaning.
Make sense?
To save the day, i'd suggest working with the same cleaner and working in one section of the fabric at a time. Turn your spray atomizer to the mist position and evenly mist the section of the seat your working on, until the fabric is very wet, evenly wet and allow it to dwell on there for maybe 5 minutes. After 5 minutes, lightly but evenly agitate the section you're working in with a soft brush then use a shop vac and go across that area very slowly to suction out as much of the dirt and cleaner as possible. This should get the rest of it equally as clean.
After you get around every panel of the seat, repeat the same process but use a spray bottle of water instead of the cleaner so you rinse all that cleaner out of the fabric and underlying foam. No need to brush the fabric on the rinsing phase.
Been down this road with lots of hired help who made the exact same mistake. This is a perfect example of what it means when people say, "Process Trumps Product".