Aside from the so-called Mind Control, are there any other instances of the Ethereals doing evil things? I have heard many people say they are evil, but I just want to know if they did other bad things aside from the so called Mind Control

I'm not a well experienced lore nerd so I'd like to know more. Image somewhat related. I mean, they united the T'au when they are on the brink of extinction and turned the T'au species nto an Empire.