I was about to open an issue for this, as i had some issues while theming the state overlay. In my solution i also removed the overlayColor usage for theming the splash, here and here, along with the relevant section on the documentation. I think this should be done because otherwise the overlayColor would be incorrectly used to theme the unrelated splashColor, violating the user's expectations and leading to confusion. What do you think about this?

@KalilDev - I agree with you that just using the splashColor to render ink splashes would be more intuitive. Undoing the existing code/doc as you've suggested would likely cause some breaks in (Google internal) golden image tests. If you'll open an issue, I'll try and address the problem in a separate PR.

Must be rolled with (internal Google link) cl/420793326