The developer of the jailbroken store Cydia has said in the forum that the store will be closed at the end of this week. There are two main reasons for the specific closure: The Cydia store has almost no revenue and recently discovered a security vulnerability may pose a security risk to users.
In the past, jailbroken users can download a variety of feature-rich plug-ins and software through the Cydia store, which is quite good for custom iOS systems.
While iOS now supports more and more features, and Apple continues to block vulnerabilities, Apple also uses cash incentives to encourage security experts to submit vulnerabilities.
There are fewer and fewer users still using the jailbreak system, and the Cydia store developers simply shut down and no longer provide maintenance and support.