Hitfilm Circle Rendering problem

Before my render of my PFP

After my render is put back into Hitfilm to use it again...

I have no idea how to stop this from looking like the edges of a coin. My PFP was made in Paint 3D at 800x800 pixels but in the project I made my PFP smaller by 50%. Resizing it to 400x400 pixels makes no difference.

This is my PFP I used. (Its also my first post/ major problem I have found with Hitfilm)