We have a big announcement in this video.iOS 15.3.1 JAILBREAK Update While the m1sta API for retrieving signed Betas was down for a few days, iOS 15.3 RC is still signed. This implies you can still save the blobs or use FutureRestore to restore them. Apart from this beta, only iOS 15.4 is signed, which is not vulnerable to known issues at this time, making it unsuitable for jailbreaking.
iOS 15.3.1 JAILBREAK Update: iOS 15.3 RC STILL SIGNED! Downgrade While You Can
The kernel vulnerability reported by Synacktiv a week and a half ago affects iOS 15.3 RC. If transformed into an exploit, Taurine and Unc0ver Jailbreak can be used to upgrade devices all the way up to iOS 15.3.1, at least for some devices. Before Apple unsigns it, you have one more chance to downgrade.
iOS 15 Jailbreak checkra1n News:https://www.gojailbreak.com/checkra1n-jailbreak-ios-15/