Plastic/carbon fibre slave cylinder and is the seals inside have removed the friction free surface and they squeak , replacement is only choice if driving you mad.
Plenty of cars moved from metal cylinders to a lighter weight plastic/carbon fibre and later these noises appeared.
Getting someone to pump the pedal and have hand on it could feel the creaking/squeaking of the unit
Item looks fairly clean and i would move the bellows back away from the arm and you will see a rod hitting the arm lube it there and see if it still squeaks as the angle on pin and clutch arm if dry will squeak. Anytime a clutch or slave cylinder is replaced we put some copper grease on cup of the arm where the rod meets it.
Black pipe as you call it is a dust cover expanding and contracting when clutch is pressed to keep internals clean