According to a post on the Metal Gear Solid Facebook page, “If you have a PS4 Pro and 4K screen, you can now enjoy [Metal Gear Solid 5: The Phantom Pain] at a higher resolution and a more stable frame rate. Even if you have a 1080p screen, you’ll still enjoy the improved performance thanks to today’s patch.”
The post also notes that this patch is applicable to Metal Gear Solid 5: The Definitive Edition. “And if you’ve got [Metal Gear Solid 5: The Definitive Experience], the patch also brings with it performance improvements to [Metal Gear Solid 5: Ground Zeroes].” According to a report from Polygon who reached out to Konami for more details, there will also be unspecified bug fixes and also support for resolution of up to 2560×1440 on 4K displays.
If you’ve yet to play the game or want to experience it on the PS4 Pro, note that the game is still free for PlayStation Plus subscribers. It is expected to remain free until the 2nd of November where it will leave the rotation, so maybe you’ll want to take advantage of this ASAP.