First time plugging in the vest. Not feeling very comfortable walking away from it which it charges..
I have that too and would say once contact has been fully established, there should be no reason to worry about it anymore. You can connect the charger the other way around (so first to Vest and then to the power outlet) to avoid that.
But that said, while a blue flashing is something I see quite regularly when plugging especially voltage adapters (with empty capacitors) into a power outlet, I have actually never seen sparks like these.
Charging is still working fine, I now just have a problem with my headphones jack. Let's see how the Woojer-Support can help me with that.
I expect these sparks are just due to the unusual high voltage that Vest uses for charging (24V), basically from an purely electrical standpoint totally normal.