Our parenting styles are completely different and it's causing issues

I'm pretty permissive - my kids love being at my place because there's fewer rules. Their mom is strict (bedtimes, screens, etc). I KNOW this is a problem. My 12yo especially is starting to use it against us like "dad lets me" and she's getting frustrated with me. I want to align with my ex but also I genuinely believe my approach is better for their development. How do we navigate this without my kids resenting the stricter rules at mom's?