Game concept
Routed Casualties
From the game's encyclopedia
In Battle, most Casualties are actually Routed Casualties and not dead or badly wounded. Unlike Fatal Casualties, these Soldiers will live to fight another day and return to the Army after the Battle is concluded. They can still be ridden down by the winning side during the Aftermath of a Battle, including if the Army voluntarily Retreats.
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.
Routed Casualties is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "In Battle, most Casualties are actually Routed Casualties and not dead or badly wounded." It is part of Soldiers. 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.