Redo the caulk at the edge of the glass frame. I’m 75% certain that’s where your problem lies… Had something similar 👍

Basically what’s happening is that water is getting out somewhere under that glass frame, going through the grout on the either side, then flowing out the side. The water could be entering all the way at the opposite end of where you see it coming out.

In fact, I’d re-caulk everything that has caulk. Don’t re-do the grout; that won’t fix anything. If re-caulking doesn’t fix it then you really do need to take the whole shower out and redo it (I know, “fuuuuuuck”). Been in that situation before too 😞