Why do my Bluetooth earbuds crackle near shop security aerials?

I'm curious about why my true wireless (is this even the current term for them?) briefly crackle and sometimes pause the music playing on my phone when going through the security tag aerials on the exits of shops / libraries.

I could understand old school analogue wireless audio that just uses fm as being susceptible to interference but bluetooth is digital right? So you expect it to stop playing or garble it in a digital way instead of noise.

Could it be a current being induced in the actual speaker wire? But that doesn't explain why music pauses the same way as if the earbuds are moved too far apart, unless it's also disrupting the bluetooth signal but I have no idea about what wavelengths are involved and if this is possible?