Note that if I set PlaceholderText during runtime, it seems to work correctly. It also seems that if I set the TextBox’s PlaceholderColor3 to something different in studio, that also returns to it’s default Color3 at runtime.
A lot of people have been reporting this since November, most people have said that it’s not enabled yet but at this point it’s really just a bug. You can use a script to set the PlaceholderText when the game’s running and it’ll work.
That’s what it was back in February. I tried it in my game when I saw it, then when I went online to look for it and it said it was implemented in actual games at the time.