I managed to find the location of the image in the PC game files, figured I'd gather the ones I have collected into a thread. I'll continue adding to this with future artwork. If you want to find it yourself, you can go into the MCOC folder and search "splash", it will pop up but in 2048x2048. You will need to adjust it to 1600x1200 for the proper image.
July 2025: Maker and High Evolutionary

August 2025: Solvarch

September 2025: Silver Samurai and Mr Knight