I had a low voltage warning once. But it only happened after I performed an update to a fresh Bullseye. When I switched my SD card to my previously used card that had Buster on it, problem never happened. Same Pi, same cable, same power.?
I since worked through the issue somehow with various updates or distro upgrades. It was definitely a software glitch (ghost in the machine). It only happened for a brief time and hasn't come back. No hardware changes so it was definitely a software issue.?
Greg Sanders