Ghostly misty white? Like in a fog?

Would it be a flat colour or shade or something that moves?

Perhaps some sort of specific background like a Tv static? Or a room/building you like similar to what some vr spaces do but recreated with splotches of colours maybe?

Or something more exotic like a constantly changing rainbow?

Would like to hear what you’d choose and why that specifically

The assumption would also be that you can’t really change it later, the choice and all the variables would be locked in, barring some minor variation perhaps ( brighter/darker or more/less vibrant for example)