Yeah, it's the fifth one I was thinking of. People say it got bad once they released the survive game
"Once" they released MGS: Survive?
Hahahahahaha. No.
Okay, here's the deal. Metal Gear Solid games are rarely up to the same level of quality without the involvement of Kojima.
Konami actively screwed over the release of Metal Gear Solid 5, by forcing it to be released unfinished (a whole 5th of the game is missing). Kojima then left the company for myriad reasons. Metal Gear Survive was released after Kojima left, and it is one of the most obvious low-effort cash-grab games in history. Not only does it reuse assets from MGS5 (fair enough), but it's so cash-grabby that you have to pay real money (after paying $60 for the game) for a
second save file.
To add insult to injury, Konami also released a Metal Gear Solid 3 "remake"
(MGS3 is generally considered the best Metal Gear game) in the form of a Pachinko Machine around the time of MGS5's release; this MGS3 "game" had original cutscenes made using the Fox Engine (the graphics engine Kojima made for MGS5), and looks absolutely beautiful.
I think there was also terrible behind the scenes stuff going on, basically Konami has been a ****show for a while. It's why nobody had any faith that Snake would come back, because the people in charge of Konami seem to actively hate video games or something.