Witching hour

I just had baby #2, she's 3 weeks old. My son was a horrible sleeper but he was a happy guy, literally just awake all the time! He never had a "witching hour" at night but our daughter does. I feel horrible because we can't seem to "fix it" then I end up feeling like a bad mom that I can't figure out what's wrong not to mention my sweet crazy 2 year old is trying to fall asleep (new baby witches on and off and won't let me put her down between ~7:30-10:30 pm). Anyone have any genius thoughts? Or even if you can empathize that's great too! 🙏