Oh if you have it set to sRGB mode then they should be accurate enough. That means it's something else. My previous monitor also had a green tint in HDR and that was just because that monitor's HDR was awful. If you want to check if it's the monitor itself, you could try it with Windows or attach a Roku/Chromecast/Firestick type device that can output HDR. If it's still green it's the monitor's fault and if it looks fine then it's Plasma's fault.

And yeah plenty of monitors have "some HDR support" it's just not real HDR unless it gets bright enough (and dark enough). The whole point of having a High Dynamic Range is that the range is well... high. Black should be black and extremely bright things should be extremely bright. A lot of monitors advertise "HDR400" or "HDR600" but don't have local dimming and only go to like 450 nits. At that level it's barely going to look different from SDR which a lot of people run at 300-400 nits anyway. The overall range of brightness is around 0.2-450 when it should be 0-1000. That 0.2 doesn't seem like a lot but if you've ever seen a completely black image in a dark room you know how not-black that is. Which is why OLED and local dimming are so important for HDR.