Can anyone help me with grout?

[MummyM33]

Ive noticed in the last few weeks that the grout in between my bathroom tiles is suddenly looking awful.
I thought it was that the grout was falling out and need replacing however in the shower this morning I noticed it was peeling away? I've never seen grout do this before. Could it be a paint or something on top of the grout? Does anyone know the best way to fix it as I'm conscious water will get in and make it even worse.
We bought our house a few months ago and the tiles were already in so I'm not sure what's been used, thanks in advance

Sorry trying to attach a pic but it won't let me

Here's a picture of it

I am no expert, but it looks like there is a very big gap between the tiles and it has been filled using silicon from one of those guns. It certainly doesn't look like grout. Does it feel plasticky? Whatever, you need to get it fixed otherwise water will get down the back of the tiles. Is it a new build?

Thank you. It could be as yes it feels very plasticy, no not a new build but the previous owners did the bathroom themselves

I was advised against tiles like that in the shower area as the space for grouting is too small to seal well, so perhaps they fixed a leak with silicone?
If it's silicone and you're happy with the look then remove the current stuff, clean with white spirit then reapply with mastic gun