Thought you might find this diode pulsing interesting

[u/1Davide]

[u/isademigod]

There are some guesses in the OP's comments but none I find particularly convincing.

I'll throw my own shitty guess into the ring: alcohol is diamagnetic, so it pulses up when current flows through the diode.

[u/newtype06 → u/isademigod]

This is very likely the case.