Game concept · By God Alone
Crisis Chapter
The game also links it as Crisis.
From the game's encyclopedia
A Crisis Chapter is The Christian Church at its most scorched:
Indulgences may be cheaper, Ecumenical Councils more frequent, Rulers may appoint their own Court Chaplain, Clergy may marry, the Head of Faith may refuse to host an Anointment and Taxes may suffer.
Saeculum Obscurum and Investiture Controversy are Crisis Chapters.
The game's text for patch 1.20.1.2. Words in blue are entries of the encyclopedia: hover one to read it, as in the game.
Crisis Chapter is an entry of Crusader Kings III's in-game encyclopedia (By God Alone). The game explains it: "A Crisis Chapter is The Christian Church at its most scorched:" It is part of Chapter Type. The game also links it as Crisis. Patch 1.20.1.2, from game/common/game_concepts/pam_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/pam_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.