She is a little girl who has discovered the earth shattering truth, that a loved parent can be lost. Also, she's seen Dad transfer the love he used to have with Mum, onto somebody new and different.
So in her mind, there will always be a fear and uncertainty about losing her remaining parent . Dad might die (because covid) . Or he might, quite soon, transfer all his old love for her, onto you.
Your marriage is pretty new, you are probably still in the honeymoon phase, very affectionate and physical. She's desperate to show him she admires and loves him just as much as you do. She's competing for the physical closeness she knows you've got.
You witness her intense love and physical affection for him, and it's making you uneasy, uncomfortable. Just pause for a minute, and wonder what unease and anxiety she feels whenever she sees you kissing and touching him, in his bed, etc.
I think she's mirroring what you do and you are mirroring what she feels .
There is nothing wrong with you and DH having a close and very physical relationship; and by the same token, there's nothing wrong with her close physical affection with her Dad. She's perfectly safe in his love and so are you. She needs to work through her feelings, and so do you.