https://www.pcgamer.com/blizzard-is-cracking-down-on-third-party-apps-in-overwatch/

Users of third-party Overwatch apps like Visor and Pursuit may soon find themselves in hot water with Blizzard, which is sending out warnings to players saying that the use of unauthorized third-party programs could lead to penalties, including a possible permaban. 

Visor provides on-the-fly stats and alerts via in-game overlays, while Pursuit focuses more on detailed after-action analysis including match histories, performance targets, and insights into how players can improve their performance. But some players, including Sabriel Mastin of Overbuff, have recently received warnings from Blizzard that "these programs provide benefits not normally achievable in the game," and that they could face sanctions if they continue to use them.