What changes to earths ozone layer have occluded in the past?

In the past, the Earth's ozone layer has experienced significant depletion primarily due to human-made chemicals, particularly chlorofluorocarbons (CFCs) and halons, which were used in refrigeration, aerosol sprays, and foam-blowing agents. This depletion led to the formation of the ozone hole, particularly over Antarctica, resulting in increased ultraviolet (UV) radiation reaching the Earth's surface. Since the implementation of the Montreal Protocol in 1987, which aimed to phase out the use of these harmful substances, the ozone layer has shown signs of recovery, although complete restoration is expected to take several decades.