We have identified a similar problem with OrangePI 3 LTE.
Seems to be a problem with AllwinerH6 and AXP805 RSB.
The code is in arm-trusted-firmware.
However, I have tried to change the speed, and it improves, but it still occurs.
When this occurs, various voltages cannot be changed.
I replaced the PMIC, but the situation did not improve.
Also, the AXP805 has an I2C communication method, which we tested on Linux, but it did not work.
When I plug and unplug the USB power supply with a fine-tuned sense, it sometimes works fine.
As far as I can see from the RSB waveform, it looks like there is a problem with the PMIC AXP805.
But I couldn't find a fix for this problem.
The arm-trusted-firmware also seems to be tied to Linux power management and rebooting, making Linux Reboot unstable.