Is that relevant? She’s certainly not a childcare professional, but even for a teen babysitting for money I would still expect adhering to the family’s routine and communicating with the parents to be a pretty normal expectation.

Maybe I’m crazy, but I would be weirded out as a parent if a babysitter told me “They were happy and mellow, but I was bored so I unplugged the router and got them to do activities with me.” Throw in a “I disagree with how much screen time you allow them” — stated or implied — and I would be irked too.

Not nearly the point that OP’s ex is; worth stating. I think punishment was unnecessary, and OP is not the asshole. I just think in his place I would also feel a bit disrespected as a parent, and I would want to talk some of these things out.

I’m surprised that makes me such an outlier, or perhaps people mistook my comment for a Y-T-A, but I stand by it.