This has been discussed at length but I will summarize for you. Reddit is charging exorbitant fees for API access and they gave an unreasonably short time to adapt. 30 days is not enough time to completely change the business model of an app, so 3p apps are shutting down. Customers have already paid for annual subscriptions to Apollo for example so the app has to keep supporting those customers or refund them. But they will cost millions just in the first year with the new API fees. The business can't survive like that, so it has to shut down.