Game concept
Secret Scheme
The game also links it as Secret Schemes, Secret.
From the game's encyclopedia
A Secret Scheme is a Scheme that progresses unbeknownst to the Scheme Target.
However, it can be discovered, causing a reduction in Success Chance, and increasing the likelihood that the Scheme Owner is discovered when the Scheme executes.
Agents that are recruited to a Secret Scheme have a chance of being Discovered.
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.
Secret Scheme is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "A Secret Scheme is a Scheme that progresses unbeknownst to the Scheme Target." It is part of Scheme. The game also links it as Secret Schemes and Secret. Patch 1.20.1.2, from game/common/game_concepts/00_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
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.