Leaking lever - Shimano brakes M365 i recently took my bike to the LBS for brake service. Everything was fine until i noticed that the right lever (back brake) was leaking.

Every time i press the lever, it sort of "burps" a bit of oil and makes... funny sounds. (seen in picture 2)

I tried un-tightening the top cap, which really helped a lot but im not sure about the origin of the problem.
I should note that when i took it to the LBS for bleeding, the pads were 80% worn. After i replaced them, the problem appeared (the mechanic said it's fine if you do that, but i doubt it). I should also note that i torture them a lot.
The first thing to check is that the rubber gasket in the brake lever reservoir is fully intact and in place. They can get both torn and clamped out of position, and that would be consistent with having just been opened up for bleeding. Make sure the reservoir is turned horizontal when open so fluid can't spill out.

If it's leaking anywhere else, there's not much that can be done other than replace the lever.