Depersonalization is not the same as anxiety/brain fog. So I'm not sure which you are experiencing. Maybe see a doctor/therapist about it? I'm not sure that I've heard about depersonalization be related to PMO but don't know what you are experiencing.
Hey, I have chronic dr for like 3 year now I don't think fapping is the cause of dp/dr but it definitely doesn't help and makes my social anxiety worse and low self esteem