Apple has stopped signing iOS 14.0.1 on the iPhone and iPadOS 14.0.1 on the iPad. This means that it is no longer possible to switch to this version. This applies to both updates and restores.
Apple released iOS 14.0.1 on September 24th. This update fixed some bugs:
Addresses an issue that could cause browsing and messaging settings to revert to their default settings after restarting your iPhone. Fixes an issue that prevented the camera from previewing on the iPhone 7 and iPhone 7 Plus. Fixes an issue that could prevent your iPhone from connecting to Wi-Fi networks. Addresses an issue that could prevent email from being sent to certain email providers. Fixes an issue that could prevent images from appearing in the Messages widget.
The latest update is iOS 14.1. It was created last week to correct many bugs. We are now waiting for iOS 14.2 which is in beta. The final version should be available very soon.
As a reminder, going back to an earlier version of iOS will be of particular interest to jailbreak enthusiasts. In this case, Checkra1n can jailbreak iOS 14. However, the tool only works with a handful of iPhones. We still have to wait for full support.