V40 1.9TDI BJ2001 – Brake fluid loss or question about brake fluid tank

Hello, the V40 of my neighbor has the problem that the clutch sometimes comes into the void. He asked me to look at it together with him. He had brake fluid after every time he had the problem with the clutch. What I noticed is the lid or the ‘balg’ under the lid. This is made of rubber and filled with air – you can press in, but blow up again. However, the bellows can’t blow up the amount of brake fluid on Max at all. so my question: Is the lid so original? No sense in my eyes at all. We filled up auif Max. lid on it – a lot of run down sideways (which according to neighbors always happens :-/) lid under again – and fill level was only still at clutch min. So probably his problem is just the funny lid. We have brake lines from front to rear k I’m curious what you’re saying. LG Matte’s PS: another question that seems strange to me: The second picture shows (probably) the AGR valve. Is that normal that it’s so open or lacks a cover here? It looks like it’s quite out there.