Could be an older version HDMI cable. I had a link with more detailed info but when I post it for some reason the comment doesn't appear.
Basically:
HDMI 1.3/1.4 supports up to 120Hz at 1080p or up to 30Hz at 4K
HDMI 2.0 supports up to 144Hz at 1080p or up to 60Hz at 4K
HDMI 2.1 supports up to 240Hz+ at 1080p or up to 120Hz at 4K