Stat Unit Frame time larger than any unit


When stat unit, I knew that the slowest unit will be critical for a frame time,
But what is the reason when frame time is way larger than any unit time?


What particular console command did you use to get this?

“stat unit”
Please ignore the lower show messages, what I asked is the stat unit result,
Since Game, Draw, GPU, RHIT unit time are all lower than 15ms, why is frame time is 20.31ms?

Is this any use?

Thanks, I will accept the VR rendering window miss penalty as the answer.