Render #pre_render callbacks must be methods of a class that implements TrustedCallbackInterface

Error in Drupal 9.0.2:
Uncaught PHP Exception Drupal\\Core\\Security\\UntrustedCallbackException: "Render #pre_render callbacks must be methods of a class that implements \\Drupal\\Core\\Security\\TrustedCallbackInterface or be an anonymous function. The callback was Drupal\\menu_multilingual\\Menu\\MenuMultilingualLinkTreeModifier::filterLinksInRenderArray. See https://www.drupal.org/node/2966725"

I have created a first patch. Maybe this one will be helpful.