Bans are manually placed on accounts following account investigation that turns up behaviour that justifies the action being taken. These investigations can be started by multiple reports of cheating or otherwise disallowed behaviour over a long time period. Alternatively, bans may be placed after the Destiny 2 app on PC detects potential cheat software and flags it, sending data to Bungie - again requiring manual confirmation for a ban to be placed. In all seriousness, and with respect, Bungie has found reasonable evidence that you have broken the Destiny code of conduct in some way and been appropriately punished for it. There is no way to appeal a ban or have it overturned. Bungie does not discuss or revoke restrictions or bans.

Typically, it’s for having a program for any game/service/etc running that can be used to cheat, hack, mod, trainer, code injectors, debuggers, ahk, etc. it does not need to be specific to D2 or actually be used....simply running such programs/software can be enough for a ban.