I have seen this over and over. When you do a brake job, you have to take off the lid and put a rag over it so the rising fluid will not spray out of the little hole.
The little hole in the top of the lid is for inlet air and is small, when pressurized by an idiot, it will spray out like a spray bottle.
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS