That's exactly right, it has to do with the RTX 2080.
I myself have three of these Samsung monitors on a GTX 980 Ti. All with UHD resolution of 3840x2160@60Hz.
This works without any problems. The card has 6GB of memory.
All monitors are connected via DP. But HDMI should also work, according to https://de.wikipedia.org/wiki... v2.0 can also do 3840x2160@60Hz.
You just have to look at the graphics card to see how many connections it has and maybe there is something in the technical data.
But it should work in any case.

I can't answer the question directly - because it's actually a question about the RTX 2080.

But for comparison: I run three screens on an integrated graphics adapter (Intel HD 630), two of them with FHD (DisplayPort and USB), the large one with 3440x1440 (HDMI). Works flawlessly with 16GB RAM (shared).

So I would be very surprised if a dedicated graphics card couldn't run two 4K screens. But whether both run at smooth 4K depends on the graphics card. However, the Samsung eats up quite a lot of resources, that's undeniable (it's currently connected as a single monitor to a mini-PC with Intel HD 605 - but with a fast 16GB RAM (shared)).

A side note: the Samsung screen is not height-adjustable and the base is relatively high - so the ergonomics are not really good unless you are a tall person.