In my view, TPLF fell because it failed to deconstruct the century-old Amara hegemony on power, economy and culture.
Mainly because of TPLF's self-awareness it represents a minority group; therefore needed to appease the Amara 3 times it's population. So, it made the official language of Ethiopia by way of the Constitution of Ethiopia.
Unwisely TPLF gave the responsibility of deconstructing Amara hegemony the less power nation groups such as Oromo, Sidama, Afara, Harare by way writing their languages while itself appeasing Amara. Even tolerated open opposition to its rule by groups from within Amara region, which ultimately morphed into the monarcky nostalgic Prosperity Party of inbred Abiot Ahmed.