CommentStreams:7f10c7075dacba47e5f0f56178b1a0d5

The flashing stopped, after the batteries were fully charged.

But for the record, the setup is as follows: Raspberry Pi 4B with RaspberryPi OS Lite on a 16GB USB thumb drive. Connected are a 4 Channel USB Relay and a USB NFC Card Reader.

If the behaviour reappears I will happily send you an image or video to your support email.