Poor NVMe performance on Zenbook UM431DA in battery mode

[Xomoxo]

System: Windows qp
Battery or AC: Battery
Model: UM431DA
Frequency of occurrence: Always
Reset OS:
Screenshot or video:
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Detailed description：
Hi,
I own a new Zenbook UM431DA notebook. I've detected that if I remove the AC power and leave it on battery more, the speed of the Nvme drive slows down from 1600MBs to 400MBs (reading or writing).
I think that this is a power saving more, but slow the drive speed to a 25% of its capability is too much. How can I solve this issue?

Thanks

[Xomoxo]

I've discovered that if hibernate the notebook and wake up it again, the speed of the Nvme is again 1.5 or 1.6gbps.
Maybe a firmware problem?