iOS 14.4.1 fixes a vulnerability in WebKit.
The new update 14.4 was released a month ago but had amemory corruption issue in the Webkitbrowsing engine.
So, with the latest update, it has been fixed.

With the new software update, Apple has also updated Safari on Mac that runs on Catalina and Mojave.
On the security page of Apple, the vulnerability was listed under CVE-2021-1844.
The security researchers of Googles Threat Analysis Group reported the vulnerability.

How to Download iOS 14.4.1, iPadOS 14.4.1?
All the iPhone 6s and above models can download iOS 14.4.1.
And for iPadOS 14.4.1 iPad Air 2 and above and iPad mini 4 and the new models.

roll out the new update by going toSettingson your machine »General » Software update.
Usually, all the macOS updates are done automatically to all the eligible models.
Download watchOS 7.3.2
On your Apple Watch download the watchOS 7.3.2.

The new OS will be iOS 14.5 which might bring small UI tweaks and new features.