This is from over a month ago so I doubt it has anything to do with Palestine.

€17.500 for a “fuck Celtic” banner which is like 1.5m x 1.5m lmfao

Ajax explicitly said that had nothing to do with him being fired.

Ajax reportedly want John van 't Schip as their new coach https://www.vi.nl/nieuws/ajax-zet-in-op-van-t-schip-als-interim-trainer

Official confirmation, Maduro will be the caretaker coach https://english.ajax.nl/articles/ajax-and-maurice-steijn-part-ways/