Does relapse occur in a single prayer only, or does it include multiple consecutive prayers such as Qiyam (night vigil prayer) and Tahajjud (late-night prayer)?

It appears the question is about reversing the order of recitation (tanqees al-qira'ah) in prayer. This is disliked (makrooh) within a single rak'ah or two rak'ahs, but not across two independent prayers. An example would be reciting a surah and then, in the same prayer, reciting a surah that precedes it in the order of the Quranic text. The same applies to reversing the order of verses.