Why was the help of Western Europe to Byzantium so weak?

This is due to the fact that the Byzantine Orthodox Church was a competitor for papal Europe. Thus, Western Europe benefited from the fall of the Byzantine Empire. So already in 1453 Byzantium was finally captured by the Ottoman Turks. True, on the other hand, this also caused great problems for Europe, since the Turks often started a war with European states, both at sea and on land.