In Jain cosmology, time is divided into two halves: Utsarpini (ascending) and Avsarpini (descending). Avsarpini is described as having six ages, with each successive age generally more morally and physically degraded than the previous. The tradition does speak of a severe decline and increasing calamities as the cycle progresses, but precise details such as a fixed 99% destruction or a specific “5th phase” ending with such a catastrophe are not stated in the canonical Jain scriptures in a universally agreed way. Different Jain sects (Digambar and Śvetāmbara) describe the phases with varying emphasis, and many details are left symbolic or descriptive rather than numerically exact.

If you’d like, I can outline the traditional six ages of Avsarpini at a high level and note where Digambar and Śvetāmbara accounts differ.