Nous A1Z and A1T bring my LED strip to flash short term although switched off


I got multiple Nous A1Z and A1T switches and they work without issues in my HA setup.

But there is one device to which I have connected a short 5V USB LED strip.
Unfortunately the LED strip flashes for a very short time (less than a second) and periodically (every few minutes) although the switch is turned off.

First I thought that the power/current/voltage measurement messes things up and turns the switch on for a very short time and thus I have disabled the reporting of this switch in HA.
But the LED is still flashing every few minutes.
I have already updated the A1Z switch to the latest firmware, but without success.

Does anybody know what could be the issue?

Thank you very much in advance!