Apart from the third beta of iOS 14.2 and iPadOS 14.2, Apple also released iOS 14.1 and iPadOS 14.1 to the public. This is the first major point release from Apple for iOS 14 and iPadOS 14 since their public release last month.
If you have been facing a lot of stability issues and bugs with your iPhone running iOS 14, you should definitely install the iOS 14.1 update as soon as possible.
At the moment, Apple has not yet released the change-log for iOS 14.1 and iPadOS 14.1 so it is unclear what changes the updates bring to the table. You can install the iOS 14.1 OTA update on your iPhone or iPad by going to Settings -> General -> Software Update and starting the download.
Update: Apple has pulled the iOS 14.1 and iPadOS 14.1 update from its developer center. It looks like the updates were meant to be released next week but were accidentally posted by the company today.