Sometimes plane do that if they overfueled. So they need to flying in circle to lower the fuel for good landing.
That as far as I know, remembering read that somewhere
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Frequently, its weather patterns dictating circling around (holding pattern) or heavy traffic especially, if the plane is too early or late from its scheduled time.
As far as "overfueled" is concerned, that shouldn’t be an issue in Morata's case. They already knew where they were going and should have the right amount of fuel for the planned flight with some extra fuel for any diversions. Usually, a fuel dump or burning excess fuel is done when after taking off, there is an emergency and you need to get back down. Sometimes, you just don’t have the time to dump fuel and you need to land over weight.
Read up Swissair flight 111 (MD-11).