My understanding is that the HDMI 2.1 port situation on TVs is, weirdly enough, a SoC limitation from a single vendor.

Almost everyone (apart from... Samsung and LG, IIRC) is using MediaTek SoC for the brains for the TVs, and they just seem to be unable to make one that has enough bandwidth for 4xHDMI 2.1.

AFAIK LG and Samsung still handle theirs in-house (and that's why LG was the very first "big" vendor to ship 2.1 at all, and they rolled it out to all four ports even on their midrange TV's in _2019_!); and it's common to see those brands have more 2.1 ports.

This should be getting better in 2025/2026 model years, since it seems MediaTek has finally managed to ship a SoC that does it; but it's ridiculous how long it's taken.