How to create a brightness gradient?

[Andy_C]

Hi everyone, I'm trying to adjust the brightness across an image in Gimp (2.10) and I'd really appreciate your help. The original image (link below) is the front of a furniture cabinet where the room was lit from a window on the left of the cabinet - the image therefore has higher exposure on the left, and is darker on the right.

 
I'm trying to adjust the image to give a more even exposure across the image. I've seen various blog posts and YouTube videos that use the gradient tool to do this. They typically use the gradient tool to fade from a dark foreground colour to a transparency. I've tried this in various ways but unfortunately the part of the image where the foreground colour is applied does not look good - the colours, contrast, and detail become washed out by the foreground colour.
Here is an example of how it looks.

I've tried using a foreground colour that has a similar colour tone to the rest of the image (rather than just black or dark grey), but this doesn't improve the image much.
 
Is there a way to create a brightness gradient? i.e. brightness is reduced on one side of the image, and gradually increases to full transparency on the other side of the image?
 
I'm relatively new to Gimp, and I'd really appreciate your help!
 
Andy_C