What happened with that huge gap? That definitely needs to be redone!

looks bad to me - but I'm not an expert.

That doesn't look right, what's the context?

Yes---it has to be redone.

It was just finished on Friday and apon closer look I noticed this spot

Yeah, it looks like the grout was too dry when applied to the tile. Make sure they dig it out of the joints and not just try to fill on top of the existing grout---it will never stay. Is this for a shower pan? If so, make sure this is cured and sealed before showering... Good Luck!

It is for the floor pan of the shower thank you!

HI -- As Natalie said -- don't let them try to just repair it , it won't last and will leak for sure . It all needs to be torn out and redone properly. They are not going to like it and will try to convince you the fix will be just fine -- it won't . Very sloppy job !

Should the whole floor be redone or just that spot

It does not all need to be torn out. It looks like someone didn't apply enough force with the grout float or only went one direction so the grout didn't fully fill the joints. Have them clean out these joints, vacuum the remains, and regrout.

Thanks I was very stressed out about this!

I'd have them redo the bad area. If you have leftover grout then they can dig out and reapply it. If a new bag of grout has to be purchased---all the grout should be removed... Chances are it will be a different dye lot and never match what's there.