Game concept

At Peace Opinion

The game also links it as At Peace.

From the game's encyclopedia

Characters who have the Warmongering Tenet as part of their Faith will have the 'At Peace Opinion' instead of the Offensive War Opinion penalty.

If you are at peace for too long, your Vassals will think less of you (if they share your Faith).

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.

At Peace Opinion is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "Characters who have the Warmongering Tenet as part of their Faith will have the 'At Peace Opinion' instead of the Offensive War Opinion penalty." The game also links it as At Peace. Patch 1.20.1.2, from game/common/game_concepts/00_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.

for a guide, post or blog

Source: game/common/game_concepts/00_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.