While your search mentions 2021, PS3 System Software Update 4.90 was actually released by Sony on February 28, 2023. If you are looking for the update from 2021, that was Version 4.88, released on June 1, 2021.

"This system software update improves system performance."

How to Download and Install PS3 Update 4.90

There are two ways to get this update on your console. The easiest method is the direct update, but if your PS3 is not connected to the internet, you will need the manual download.

Sony released PS3 System Software 4.90 on February 28, 2023, rather than 2021, focusing on performance improvements and updated AACS encryption keys for Blu-ray drives

It has been over half a decade since Sony officially discontinued the PlayStation 3, yet the iconic black console refuses to fade into obsolescence. In late 2021 and early 2022, Sony surprised the gaming community by rolling out a series of firmware patches, culminating in the now-famous Version 4.90 update.