I have 2 adopted DDs of 11 and 8, and this is something they do it a lot. I used to worry a lot about it, but I can now see that they're both very fit (they're both good gymnasts) and very healthy, so it bothers me less now. Their behaviour includes fussiness over food; they'll suddenly decide that they don't like something that they previously had no problems with.
I don't think it's manipulative, but it is about wanting our attention; negative attention is still attention so it's actually encouraging the behaviour, I've found. I used to really worry, wondering whether it was connected to their being adopted, but it's very easy to make everything about adoption when of course that isn't the case.
I'm sure that in your DSD's case, she is craving time with her parents, which is understandable. My DSis was the primary carer for her DSS during his teen years, and it was tough for her (and he was a very well behaved boy normally), but the adults involved were all on the same page, so they made it work. He has 3 younger siblings that my DSis had with his dad, so it could have gone badly wrong, but he's now a lovely, well balanced young man.
I think it's not helpful to put a negative spin on children's behaviour at that age, your DSD's behaviour is very reminiscent of my DD2's behaviour since lockdown.