Discord Nitro subscription will no longer offer access to a vault of games because apparently, the vast majority of subscribers didn't even use the feature.
Discord recently announced that they are parting ways with some annual contracts, one of them regarding the free games vault. While technically not free because users were paying a subscription to access these games, that's what Discord calls them.
Anyway, these free games will no longer be a thing come 15 October 2019. The reason for this is that the vast majority of Discord Nitro subscribers didn't even play them , despite the vault having some gems like Tyranny, Wasteland 2, Metro 2033 and Last Light.
Another thing that these great games have in common is that they are old, which is possibly the reason not many Nitro subscribers were playing them. Out of the four games mentioned, Tyranny is the newest one, having released in 2016, meaning that whoever was interested in playing these games, they had at least three years to do so by the time of writing.
As for the more recent games that people actually bought on Discord's store, they will be unaffected. Any games you may have purchased on the platform will remain there and it will not just snatch something you paid for. The same goes for any game perks gained through Nitro subscription such as the monthly rewards for Warframe, Warface and Paladins.
Still, Discord Nitro will keep offering other benefits such as Server Boosting as well as adding new features. One such feature is the increased upload size of 100MB for the $9.99 Nitro subscribers.
Anyway, it seems like Discord has given up on gaining any revenue through game sales, which is not that odd considering one had to join a game's Discord server and purchase it from there, as opposed to having a proper way of browsing the offerings.