Apple released iOS 14.4.1 last week, and as is traditional, Apple has now stopped signing iOS 14.4, making downgrading to that version of iOS no longer possible.
Version 14.4.1 includes important security updates and is recommended for all users.
An Apple security support document says that the updates fix a WebKit bug that could allow maliciously crafted web content to arbitrarily execute code.
WebKit
Available for: iPhone 6s and later, iPad Air 2 and later, iPad mini 4 and later, and iPod touch (7th generation)
Impact: Processing maliciously crafted web content may lead to arbitrary code execution
Description: A memory corruption issue was addressed with improved validation.
CVE-2021-1844: Clément Lecigne of Google’s Threat Analysis Group, Alison Huffman of Microsoft Browser Vulnerability Research
Apple is known to routinely stop signing older versions of operating systems after it releases a public update, as part of an effort to encourage users to keep their devices’ operating systems up to date. Restoring devices to older iOS builds is common for users with jailbroken devices.