Apple stops signing iOS 14.0.1 after releasing iOS 14.1. If you upgraded your device OS to iOS 14.1 it is not possible to downgrade to iOS 14.0.1. Apple frequently releasing new iOS versions with bug fixes, performance improvements, and adding new features. And they stop singing old iOS versions to prevent downgrades.
Apple might focus on users to keep the latest iOS versions on their devices. Also, they are trying to prevent jailbreaking.
When we talk about iOS 14 jailbreak checkra1n is the only jailbreak tool released for iOS 14, iOS 14.0.1 and iOS 14.1 versions. And checkra1n is a hardware-based jailbreak tool and supported a limited number of iPhone and iPad devices on iOS 14 - iOS 14.1. Newest devices running on iOS 14 - iOS 14.1 can not be jailbroken using checkra1n.
So it is not a huge problem for new device users with iOS 14.1. As iOS 14.0.1 can not jailbreak for new devices they do not need to downgrade to the previous version iOS 14.0.1. So they can enjoy the brand new iOS 14.1 with bug fixes and performance enhancements.
Also, this downgrade prevention is not a problem for old device users as iOS 14.1 already jailbroken using checkra1n.
However, if you already saved blobs of iOS 14.0.1 you can still downgrade to your device iOS version to iOS 14.0.1 from iOS 14.1.