Sometimes I can see a ghost of previous windows if left in the same spot for an extended period of time.

I had this problem in two of my U2718Q monitors, but one of them suddenly decided to stop working. Had to replace the main board of the monitor, and now it works. Additionally it also seems to have no issues with burn-in anymore. Ran it on 100% brightness with a white/bright window for roughly one hour, then dragged a black/dark window over it to check. Probably not relevant, but it was tested on macOS Monterey on a 14" MacBook Pro M1 using HDMI. Not confirmed, but presumably with the monitors suffering from slight burn-in, it helps to run them at less than 100% brightness.

That looks like an okay part to use. I've written a decent-ish teardown you can reference. Although with this being almost 3 years old now, you presumably have found another solution to this issue. Maybe someone else finds this useful though.

You could in theory replace the display on this, but I'm not sure if you can just get a new display and put it in. Presumably the display is connected to some hardware/firmware combination that expects this particular display. So unless Steelseries opened up a spare part shop, where you could buy replacement parts, the official answer is; no. However, you can (probably) buy broken base stations to use for spare parts, depending on what's broken of course. Here is an image of the screen part, which I guess is glued in some plastic frame thing that sits inside the base station enclosure. Side note! It's not really too bad to take the base station apart to replace parts in it. Just have to slightly lift the glued rubber base in each corner to find the screws, then carefully loosen the clips. Though be careful, this base station is very clearly not meant to be taken apart with ease, so some of the wires are very short and soldered on to the PCBs.

If I remember correctly, yes. I haven’t taken it apart, because it’s not possible without destroying it.

FCC has some pics of the internals I think.