The PlayStation Store will remove the ability to purchase or rent movies and TV shows on 31st August 2021.
Any existing content you have purchased will remain yours to view, and you'll still be able to access this via the PlayStation Store on all your devices. You just won't be able to buy more, and have to get Netflix instead.
Explaining the change via the PlayStation blog, PlayStation pointed to the shift away from owning individual movies or boxsets. People are now more likely to just stream content from a subscription-based service (such as Disney+ or Amazon Prime) or one that's free but includes ads (such as ITV Hub or All 4).