And this is just a manufactured rightwing "controversy". The museum had been doing this for months (it's literally just 4 hours a week) without issue until a radio station associated with Germany's far-right saw something they could spin as anti-white to rile up the "oppressed" white whiners on far-right Twitter.
The German version of this story has more information, but frankly it should have been obvious to all these "reverse racism" whiners that it was just a BS rightwing controversy regular people shouldn't give two shits about. The associated party, AfD, is Germany's far-right racist party, which has been ruled in court to be legitimately suspected to be a "threat to democracy".