The funny thing is the disc you think is 4K with black writing on it and says ultra is the 1080 disc and the red writing disc is the 4K disc
Assuming, which seems likely, your version follows my Deadpool 2 SuperDuper cut set: your statement is not true.
The Black disk, labeled "UltraHD Premium" and with a notice early in the pre-play screens that it's HDR, is 4k, HDR, is 4k and has Atmos.
The Red Disk, labeled merely Bluray and without said warning, is a standard bluray.
I've even validate this belief by attempting both in a non-4k player. Only the red disk was readable.