I was just about to create a similar thread. Not sure if this is the same thing that OP experiences, but it seems that common video players like MPC and VLC are unable to render the video properly. I have never really paid attention so it's possible that it always used to be like this.
If you were to open the images in a new tab and quickly switch between them you would notice that printscreen and splash images are almost the same (just some quality loss) and then what MPC sees is totally different. That's how the video playback looks as well so it's not something with image compression (i have the of original .bmp files and it's the same).
Haven't tested how the files look in Premiere or YouTube.
PrintScreen:
Image saved with Splash:
Image saved with MPC-HC:
PrintScreen:
Image saved with Splash:
Image saved with MPC-HC: