You can check current power mode starus like this.
nvme get-feature /dev/nvme0 -f 2 get-feature:0x02 (Power Management), Current value:0x00000004
'''<big>More info when available.</big>'''
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PSU I use is 20W that I use before so it's checked. I never saw under-voltage alarm on RPI5 itself. Same four drives connected on 4x4x4x4 bifurcatated PCIe3 slot on PC are performing like a beasts. Now I'm having stable configuration using both RaidZ1 and 2 by software limiting IO bursts to drives.