Sony has not declared it as the last. However, given the PS3’s age, 4.90 may be one of the final updates. The previous update (4.89) was released in 2023. If another critical security patch is needed, Sony could release 4.91, but nothing is confirmed.
Use this if your console cannot connect to the internet or if you need to reinstall the software. How to update PS3 console system software - PlayStation playstation 3 system software update 4.90 download