That is not grout in that section.
That is either caulk with grout layered on top of it
Caulk that looks like grout.
Grout does not curl when it is installed incorrectly, it cracks and breaks off in chunks.
You can caulk over grout at tub top but cannot grout over caulk (and caulk that looks like grout is usually crap).
Since the gaps are on the larger side - not obscene but larger - I would try to grout the area... see if it lasts without cracking and then silicone over it if you notice it cracking.
If you try to apply silicone you will need to go deep into cracks (1/4-1/2"), get an edge, let it dry and do another round or two of caulking. You cannot do all of that silicone at once or when it cures and you have a failure piece, the whole system will come out in chunks of silicone.
So here it is - The yellow highlight... that's grout. The red circle is an example of an area (not the only area) that is not grout. The webbing at the top of the "grout" shows it is not grout as grout doesn't do that, ever. You see how dry the yellow area is, that is what grout looks like. Grout cracks in large lines/chunks.
Also if there is caulk on grout - what some are suggesting and maybe...
- Wow when you grout you fill the damn gap if this is the case I am not even sure if they filled half the gap.
- The caulk wasn't silicone (should be) - silicone doesn't dry or peel like that. Sure looks like caulk that looks like grout.