Users can upgrade to iOS 13.2.2.
On November 8th, Apple rolled out iOS 13.2.2 to all users, fixing many bugs (including the issue causing background apps to unexpectedly quit). A week later, which is today, iOS 13.2 code signing has stopped, and users who have already upgraded can no longer download iOS 13.2 from Apple's servers.
iOS 13.2.2 includes bug fixes and improvements for iPhone:
• Fixed the issue that could cause background running apps to unexpectedly quit
• Resolved the problem where iPhone may temporarily lose cellular network service after ending a call
• Fixed the issue where cellular data may be temporarily unavailable
• Fixed the issue that prevented reading replies to S/MIME encrypted emails between Exchange accounts
• Resolved the issue where Safari may prompt for authentication when using Kerberos single sign-on services
• Fixed the issue where YubiKey accessories powered by Lightning port may experience charging interruptions
Apple's timely closure of the iOS 13.2 downgrade is also due to the numerous system issues present in that official version. Additionally, the known "checkm8" vulnerability has garnered attention, providing jailbreak possibilities for iPhones, including iPhone X.
Earlier this week, Apple just released the second beta of iOS 13.3, making some minor adjustments and fixes to the system. Of note is the support for NFC, USB, and Lightning security keys in Safari.