Much of the PCV stuff I found on eBay to be very poor quality.
The valve I had wouldn't hold boost, just hopeless (there is a small valve in the T-piece under the inlet). The valve closes off under boost so it's not lost back to the intake. At idle, the valve opens and draws a measured amount of crank gas into the inlet for combustion. This keeps the crank clear of condensation and gathered blow by gases (which includes fuel). These gases contaminate the oil.
OEM is near £200 for the complete kit.
Delete it all. Silicone hoses and catch can. However, you lose positive crank case ventilation which is a very good thing at idle / low RPM.
So, if you do delete and potter about in town, make sure you change oil on a 6k mile interval. As it's the oil that suffers.
At higher RPM the blow by gases are much larger causing 'self venting' of the crank via the hockey puck back into the intake tract. The cam area also vents by the same route, guessing the cam area gets slightly pressurised by valve seal leaks etc and the passing crank gas draws it out. Note the shape of the bit you are pointing at, it's by design, to draw gases out of the cam area.