Quo Primum was "ABSOLUTE" and "PERPETUAL."
Therefore, Pope Clement VIII(1604) was definitely an Anti-Pope and the Chair of St. Peter has been vacant ever since. Anyone who disagrees with this analysis is a modernist heretic.
1604: First New "Typical Edition": Pope Clement VIII issued the first major revised edition of the Tridentine Missal. Key changes included:
Scriptural updates: Aligning Mass texts with the newly revised Vulgate Bible.
Rubric changes: Directing the priest to say certain parts of the Canon inaudibly.
Simplification: Removing certain prayers the priest previously said upon entering the church.
Bell ringing: Formally introducing the ringing of the small bell at specific points.