How do you deal with really intense parental preference and separation anxiety?

My 2.5yo is having a meltdown at bedtime any time her dad puts her to bed. Since she was born we’ve done bedtime together; I nurse her, give her vitamins, brush teeth, take her to the potty, and put on her diaper and jammies. Dad reads stories, sings her lullaby, and puts her in bed. We’ve had this routine basically forever. But in the past few weeks, she has been resisting everything, messing around, stalling etc etc which I know is normal, but she has an absolute screaming crying meltdown when it’s time to say goodnight to me.

This happens at nap time as well, when I put her down in her crib she has started crying quite a bit and always asking for more hugs, more kisses, more mommy. It’s not quite as bad at nap time, when it’s only me there, but it’s still not great.

We’ve tried having my husband do her whole bedtime too, but she melts down when we say it’s time to go upstairs and I’m not going up, even though I prepare her and tell her all day long that daddy will be doing her bedtime tonight. We’ve tried giving them a “secret handshake” so that bedtime with dad is special. We’ve tried adjusting her bedtime (but I really don’t think she’s over or under tired.) We’ve tried putting a picture of me in her room. I taught her to feel her heartbeat and mine, and I told her when she misses me to put her hand on her heart and it’s my heart talking to hers to keep her company. Nothing seems to be working.

Tonight was the worst, she was clinging to my legs, wouldn’t let me go, nails digging into me. I don’t understand why she’s so resistant to her dad. She spends ALL DAY asking me when daddy will be home, gets insanely excited when he walks in the door, wants to sit in his lap and read books and play, wants him to come sit in the room while I nurse her at bedtime. But then when it’s time for me to leave suddenly it’s “no daddy. More mommy”

Does anyone have any other tips or tricks that we could try?