How would you make a responsive shape like this?

Hi everyone,

I am at the edge of my sanity here. I’m trying to make a modular / responsive material for my UI that has a slightly strange shape (angled cut at the top left, rounded corner at the bottom right).
The rounded corner on the bottom is easy, I just use an sdf box, but I cannot, for the life of me, figure out how to do the top left without it stretching if the material is anything but a 1:1 aspect ratio.

I’ve tried linear gradients, image textures, rotation of a gradient based on the aspect ratio difference, and I can’t get it to work…

ANY idea would be appreciated!

Bonus if you have any sort of info on where I can find documentation on 9 slice scaling images in the material graph editor (Google, Youtube & ChatGPT have been useless so far), since that way I could easily make a texture that handles all of this.