Saurik disabled purchases in the Cydia Store on Thursday in an effort to protect users from a bug that could result in arbitrary PayPal purchases. You can still buy jailbreak tweaks from third-party repositories, however.
Hot off the heels of a recently-announced security vulnerability for iOS 12.0-12.0.1, another individual has released an exploit that targets iOS 12.1 and below. Some tweaking is required to make it work, however.
If you have used third-party apps to artificially boost your popularity on Instagram, you might be interested to learn that all those fake likes, comments and follows that you basically bought will soon get nuked form orbit.