Kitten Possibly being Rejected

EDIT: PLEASE DO NOT MAKE THE SAME MISTAKE I MADE
After looking more into it, it's better to leave kittens with their mothers. It helps their immune system and keeps them healthier. Mama knows best. Human does not. Seems like basic knowledge but I really thought I was helping. I'm so glad most of them survived, but I wonder would Berlin and the other two have survived if I didn't intervene? I felt like some of them would have passed if I didn't. We don't give animals enough credit sometimes. They know what they're doing and they don't always need our help.

I have some deep regrets but this was such a learning experience. Please think twice before taking a kitten away from its mother.

Here is a video of Berlin's story and some signs of possible rejection from cat mothers, and what to look for with fading kitten syndrome most found among feral cats.