Sony has a habit of linking its line-up of PlayStation Plus games with upcoming releases or announcements, and May is a great example of that.
Because we're just days away from the official reveal of the new Battlefield, so Sony and EA have decided to make Battlefield V one of May's PlayStation Plus games. It's obviously not the only one either, as PS Plus members will also get Stranded Deep and the PlayStation 5 version of Wreckfest. All of these will replace Oddworld: Soulstorm, Days Gone and Zombie Army 4: Dead War as "free" games on May 4, so grab the latter ones while you still can.