Didn't Dany tell Yara she could be Queen of the Iron Islands?
Since she asked nicely and agreed to pledge her loyalty or whatever? So what's the issue with Jon remaining the King in the North so long as he does the same?
They really didn't handle that well at all. Yara with no authority after losing at the Kingsmoot agreed that the Ironborn would change their entire way of life in exchange for the title Queen and Dany said OK, that's fine. But now she's obsessed with asserting her power and tolerating no dissent?