They didn't "have" players "take the knee", they just didn't stop them. It's called freedom.

Freedom as long as it’s a cause officially sanctioned by the league.

Which cause did players want to support but were forbidden from?

Probably Palestine related issues. Can they even talk about that stuff there without getting arrested?

Not FIFA specific but during early 2020s players were forbidden to support skipping the vaccine

	▲	Kuyawa 6 minutes ago \| parent [-]
		[dead]

Jtarii an hour ago | parent | prev [-]

Has the league sanctioned players taking a knee for other causes?