Why did Habsburg forces lose Belgrade in 1690 after capturing it in 1688?

Habsburg forces lost Belgrade in 1690 primarily because the outbreak of the War of the Grand Alliance against France necessitated the diversion of military resources away from the Turkish front.1

Following the successful capture of Belgrade in 1688, the Habsburg military became overextended when Louis XIV launched an offensive against the German Palatinate. Because the empire could no longer spare the troops required to maintain its southern conquests, it was forced to abandon its positions, including Belgrade, in 1690. This retreat left the local population, who had risen in support of the Austrian invasion, vulnerable to Turkish reprisals.123