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Read through many pages about the Yongnuos via your Lin and saw your last few posts. Are you ab b800s speed lights or strobes? Not sure if you caught it, but Stobes use a hack to emulate HSS called super sync, and with the 622s if the strobe/flash does not natively support High Soeed asynchronous, then you must use the PC sync cable from the 622 and connect to the strobe to let the emulation work. Down side of the emulation is falloff etc. if your b800 doesn't natively support HSS and you didn't use the sync cable, it will fire, but not properly timed for the moving shutter curtain slit of HSS and can reduce light, miss, or create gradient. My guess is that you call into this later situation.
From this how would you diagnose your results?
Also, You can experiment by locking in manual ss and aperture for a test HSS with ettl for flash output, and then walk the shutter speed over a range to see of exposure is maintained at all in HSS. I understand the PCN connect cables are cheap cables on eBay. I would be very curious for your summarized results.