Hi @brivaelle - that behaviour is expected. The splitscreen tool disables all color processing including the input and output color space transforms. What you see on the left side is the actual image with no color space transforms applied. To toggle between a before and after that only includes the creative processes you can do one of the following options:

1. Long-press and hold on the image to show the unedited original. Release to show the edited image.
2. Drag the global mix slider to 0 to reveal the unedited image. You can also long-press and hold that slider to snap it to 0%. When you release, it snaps back to the previous position. This also works for individual color modules with a mixer.

The reason the split screen behaves differently is to cover another legitimate use case of the application:
When developing RAW images in Color.io, we initially treat the RAW file like a cinema camera by encoding the signal with a logarithmic gamma. Color.io is also used by many to work directly with log encoded material from actual cinema cameras like the Arri Alexa. The first step in grading this kind of material is to normalize the log gamma with an appropriate input transform. For RAW images that would be VisionLog RAW, for an Arri Alexa that would be Arri Log-C. Colorists need a way to compare this unmodified and flat base image against the final grade that includes the input and output device transforms.