Microsoft ended support for Windows 8.1

Microsoft recently announced that support for Windows 8.1 ended on January 10, 2023, and all PCs running Windows 8.1 will not receive technical support, software updates, and patches for any problems from Microsoft.
In the announcement, Microsoft also emphasized that it will not provide Windows 8.1 with an extended security update (ESU) program. And Windows 7 has this plan, but it is mainly for business users, and you need to pay to get it. In addition to embedded systems, ESU support for several major versions of Windows 7 also ended on January 10, 2023.
Windows Server Insider Preview Build 18945

Compared with Windows 7’s 14 years of update support including ESU, Windows 8’s only 11 years of support seems to be a little short. Due to the adoption of a design style closer to mobile touch-screen devices, many people said that they were not used to Windows 8 at the time and continued to use Windows 7, so the shortened support time seems reasonable.
For users who are still using Windows 8.1, Microsoft recommends buying a new computer with Windows 11 or upgrading the computer to Windows 10 or Windows 11 as soon as possible. Microsoft also emphasized that Windows 8.1 cannot be upgraded to Windows 10 and Windows 11 for free.

Considering that most computers in the Windows 8.1 period already use UEFI boot and GPT partitions, technically speaking, upgrading to Windows 10 does not require many operations. And because Windows 11 has strict requirements on TPM and processor, it may be more difficult to upgrade these computers to Windows 11.