So, I actually went through this myself. My dad would let me get away with murder and he would be so strict with my brother. It used to break my heart seeing him get told off so much knowing that if I did the same thing it would be fine. I wouldn’t say my brother resented him as we got older, it was more pain and hurt, Like you could see it in his eyes he never understood why he was treated so different to me. My brother passed away so I can’t comment on how the relationship is now but I know my dad has massive regrets. Xx
Maybe he feels guilty that he doesn’t see his daughter as much as your child you have together so he feels like he has to spoil her a bit to make up for it?
I think it’s more gender based than favoritism. Dad tends to be softer on their daughters cause they have more of a soft spot for girl than with their sons. Since they are men, they feel they need to be more stern and tough. I would talk to him about it more and the gender aspect of this.
If he sees his daughter less he won't want that time taken up by telling her off, that said, she shouldn't be able to get away with murder and he shouldn't be screaming at you in front of your children. Try having a conversation when there's no children around and you're both calm because it will start to cause a wedge if not
I’m not in a situation like this personally, but when I was reading this I thought maybe he treats his child from a previous relationship this way when she is with you because he wouldn’t want her going back to whoever it is has her aswell ( I will presume mum?) and say that he is being mean to her/ treating her bad? I know it sounds silly but he may feel scared that he may end up not getting to see her anymore if he tells her off. Maybe have a conversation with him and try and get the jist of why he acts this way when she is around. It’s not fair for him to treat your child together any different than the child he has previously x