Announced alongside the latest PlayStation Plus title for May was the detail that the PlayStation Plus Collection--a lineup of 20 games that PS5 users can access so long as they have PS+--will be losing one of its games. In May, Persona 5 will be removed from the collection, with no official reason being given for its removal. However, so long as PlayStation Plus users claim the game prior to May 11th, they'll be able to keep it and still play it, so long as they have an active subscription.
The PS Plus Collection first kicked off in November 2020, to celebrate the launch of the PlayStation 5 and to celebrate its backward compatible capabilities. The other 19 titles will still continue to be available, even after the upcoming rebranding of PS Plus.
Persona 5 will leave the PS Plus Collection on May 11. Add the game to your game library before then to continue to access it while you have an active PlayStation Plus subscription.