Doubt about white pastry on all my boards

I just recieved some sonoff RF R2 boards and all of them have a masive amount of white pastry over the transitor, I am worried because when a board explodes it drop the same pastry.
So the question is: is that white pastry normal on new devices?
I attached a pic.

It’s hot glue/caulk. No worries whatsoever.
It prevents noise from the transformer.

Thanks, I really appreciate your reply. Lots of device are the same and some not. Thanks