it could be a joint where they didnt pack it in the greatest and when they wiped it out they accidently took a touch too much out of the joint.

@Distinction Tile

Is there a way to fix it?

Scrape it all out and reapply. Grout can be removed easiest as soon as possible after application, the longer it sits the harder it gets.

@Stephanie Woodley since its flex color grout i believe you can just add a touch of it up there and wipe it off easily or scrape it out and quick re pack it. If it happens again then its possible its a movement issue thats causing a crack in the grout.