How can I rectify this wall?

[Newuswr]

This wall is in the bathroom adjacent to the bathtub/shower. I’m not sure how, but the skirting board seems to have widened. The textured bit of the skirting board seems to be raised in comparison to the rest of it. What are the steps to prevent this from getting worse and stop this from happening?

There usually is a large cabinet that sits in front of this space so water doesn’t usually hit the wall, nor does anything physically touch the skirting board to damage it. I just moved the cabinet to find this!

It's MDF and it has got damp and stayed damp. The only way to fix it is to replace it. If you do like for like MDF then it will need to be sealed properly before being attached. wood would need sealed too, might be best to look at replacing it all with plastic.

Exactly as PP above says.
We had a similar problem. Water was trickling down the side of the bath from an Ill fitting showerscreen and pooling on the floor. Gets soaked up by the MDF skirting which expands (irreversibly).
You'll have to pry it off and replace or change the whole bath panel if you want rid.
Or, if you can learn to live with it, paint the bath panel and skirting again to make it more water resistant and run a bit of sealant where the floor and skirting meet to prevent further wicking.

Ooh, just to add, if you are absolutely 100% sure it's nothing trickling down the side you had better check for a leak under the bath - there's no doubt the MDF has got wet I'm afraid.....

Oh interesting. Do you think the bathtub might be contributing?

Can you see where the side of it is curved in the photo? The edge is supposed to be straight but now it’s warped. It’s also not sealed against the wall.

Sorry forgot to actually add the photo

Yup 100% it's getting wet - it could just be from water sploshing over the side of the bath or getting on the floor when people get in and out. Is there a shower at that end?

The shower is on the other end.

There’s usually a cabinet in front of that wall that water would generally splash on first, it hasn’t got wet to a significant extent but the room has no ventilation or windows either. I think the bath panel would need to be replaced too.

Oh OK, that second picture helps. I thought, from your first picture we were looking at an MDF skirting that had been put along the bottom of the bath panel, my bad, bath panel looks fine.
Soooooo, is the floor damp or cold at all within the area I've drawn a line along in attached pic? I'm wondering if water is getting under your flooring somehow.. Leaky pipe somewhere? And then getting sucked up by the skirting...

Is it an outside wall behind the bath? Asking as if there is normally a cabinet in place, it might be condensation collecting on the cold surface, then trickling down to the skirting, especially as you say there is no window, or ventilation. Do you have a fan to extract moisture from showering?

Best thing is not to put the cabinet back and see whether it dries out, or stays damp. If it dries, then lack of airflow behind the cabinet is the most likely problem, but if it stays wet, then something else is at play.

Keep the room ventilated by keeping the door open as much as possible.