KDE suports HDR just fine. I believe both Hyprland and Gnome do as well. Those seem to be the most modern DEs generally speaking. Gnome and KDE being the most popular as well.
Edit: Just realized you said mint specifically. Mint are behind the times sadly.
Man hackers would love you. Memory vulnerabilities are still one of if not the main cause of vulnerabilities in unsafe languages. Yes this even applies to large projects ran by experienced and skilled people like the Linux kernel. Stop thinking your the exception, because I guarantee you aren’t but even if you were you can’t read all of the code in the world in your lifetime. Nor can you write all the code in the world.
I am also on CachyOS and KDE here. It was a good find. Seems to be getting more popular and well known over time.