Hi focusing obsessively on people is about the ADHD mind wandering problem as a whole, fantasising, planning, wanting interest and novelty etc! I remind myself of that when it happens and tell myself to ease off. Regular practice of mindfulness to train the wandering mind has most helped me over the years!
I hope this helps you. Yes I’m sure it’s common it’s part of the ADHD brain, but we can lessen the effects on life and our reactions by building our mindfulness muscle!! It takes time and practice though, but good on you that you’re aware of the problem!