sous vide is largely about getting the doneness correct, by hitting a temperature for a length of time. the temperature largely affects the doneness, as does time, but time can also alter the texture.
have a look at the links here for some examples: Cooking much longer than the recipes I find online? - #4 by Walter_Ego
once you have hit the correct doneness/texture, you then need to undertake finishing steps (searing, etc…) to get the flavour/external colour/etc… you’re going for.
i have no idea about op though, could be a lot of things.