Sony has officially announced they are no long supporting the PlayStation Store on the PS3/PSP/PS Vita. While it is a blow to people who were looking to make more purchases on their older PlayStation consoles, no need to worry as every game you have purchased are still available to download through the respective download list when using the consoles. Another thing to note online stores for these platforms will not show up when browsing the stores through a web browser.
Sony is planning to retire each store in phases, PS3 and PSP will happen on July 2nd, 2021. While the PS Vita Store will retire on the 27th of August 2021. Here is a brief snippet Sony has released for more information on which features will no longer be available over at https://www.playstation.com/en-gb/support/important-notice/