I completed a compression test which showed that cylinders 1,3, and 4 had compression of 180psi and cylinder number 2 had a low compression reading of 150

Upon disassembling and removing my b18b cylinder head, i noticed that 2 exhaust valves on one cylinder (number 2) were of an off white colour compared to all the other valves being a charcoal colour, and also the piston in this cylinder (number 2) is dry compared to the other pistons as show in the picture also.
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I'm unsure what has caused this problem and what will need to be fixed/ replaced to fix the problem