Game concept
Buy Artifact Claim
The game also links it as Buy Artifact Claim Interaction.
From the game's encyclopedia
An Interaction that allows a character to buy Personal Artifact Claims in exchange for Piety or Prestige.
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.
Buy Artifact Claim is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "An Interaction that allows a character to buy Personal Artifact Claims in exchange for Piety or Prestige." It is part of Interaction. The game also links it as Buy Artifact Claim Interaction. 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.