HDMI 2.1 carries more bandwidth than DisplayPort 1.4. Plenty of GPU/monitors have that port arrangement, as recent as Nvidia's RTX 40 Series.
I'd say it's usual for displays released in the 2-5 years old range. HDMI 2.1 got somewhat quick monitor support for consoles, but search for "first DP2.1 monitor" gets results from 2024
TVs.
DSC is just the "card up the sleeve" for DP1.4, you can push it all the way to 4K 240hz HDR. So there is little incentive to switch to DP2.1 for OEMs.
It's just nice when technology is not hampered by nonsense.
Dell U5226KW from 2026 only has DP1.4 (but HDMI 2.1).
I don't think I have seen anything above DP1.4 in the wild for now.