Yeah, that's not ideal. As long as it's not actually holding the GPU's weight up, it's probably ok-ish, but not an good idea to have actual pressure on it. Is your GPU sagging (hard to tell in that pic), so maybe a GPU support bracket might reduce the pressure a bit? The problem is mostly due to the high spec connector on that RGB cable, with its big moulded strain relief sticking up a bit too far. You could try to find a RGB cable with a lower profile connector, as they don't really need to be quite that big; either to completely replace that cable or an extension for it. The ARGB cables which ASUS supply with products are a lot more minimal, for example, although I don't know if you'd be able to buy them separately.
Edit: The connector doesn't really need to be any bigger or fancier than the smaller one immediately below it (a fan cable, I'd guess). That's what I mean by lower profile, something a bit more like that.
