DSC使ってるかも
It's possible this display might use DSC.

5120x1440 at 240Hz with 10bit RGB and a DSC compression ratio of 2.5x is a data rate of 24.25Gbps, fitting just within DisplayPort 1.4's 25.92Gbps data rate.
https://www.reddit.com/r/hardware/comments/epueys/samsung_odyssey_g9_49_curved_5k_240_hz_freesync/fem3c19/?utm_source=amp&utm_medium=&utm_content=comment_timestamp