These images are AI generated stadiums that you can use for any leagues you create. These are the background images used on the pre and post game screen.
There retro 50s and 60s era sets with clear, rain, and snow versions. these would go in your "common" folder, the location would look something like below:
My league is the GFL, and the art folder is GFL, so

D:\psf2026\images\GFL\common\default\backgrounds\16_9

These are all 16x9 resolution, and all the image files would go in the above 16_9 folder.
You would have to rename the images to match the team you want to use them. Look at your
midfield logo for instance, if your tigers team art all starts with tigers_midfield_logo, you 
would name the 3 stadium images tigers_background_clear,  tigers_background_rain, and
tigers_background_snow.

I used Google AI Studio for some of these, you can try it at this link

https://aistudio.google.com/prompts/new_chat

The prompt to create them was something like:
"Please create a modern American football stadium, in an urban setting"

I would change the "in an urban setting" part to 
-with a mountain background
-in a coastal area
-in a busy downtown
etc.

After a stadium image is created and you like it, type
"Please add overcast sky, heavy snowfall and snow on the ground"
"Please add overcast sky, heavy rainfall and wet streets"

Use your own variations.