I see you as having 4 perfect games: CS2, GTAV, Slime Rancher and Retail Company.
What is the game you think you are missing?

The only game i see that you are closing to perfect is Terraria 114 out of 115 achievements

No, I'm not saying that something is missing, I just saw that someone in the library has an icon of a perfect game on the cover of the game, not in the profile, but in the library itself

If it's not on the profile then that means the game has ''profile limited features''. It will remain this way until the game meets certain steam requirements such as x amount of the game copies sold ect.., once they reach the requirement the limited features is lifted and will appear on your profile showcases.