It's probably due to fixed heights.
Looking again, I found the .content-games-item class has min-height: 450px and max-height: 450px; set to it.
Generally you shouldn avoid forcing the height (at least not max-height), You're already using display: grid on the cards container, their height will be automatically adapted to the longest one, if the button seems to stick on top leaving a gap, you can push down them by expanding the flex items above with flex: 1 or by setting a margin-[top|block-start]: auto on the buttons container.
Hope it helps you, keep it up!