Technically speaking, what is the reason why the 5070 Ti seems to be on par with the 4080 SUPER at 4K resolution while the latter is almost always two steps ahead the former at 1080p and 1440p?

I have been seeing lots of benchmarks between the two, and when I look at the 1080p/1440p comparisons, the 5070 Ti doesn't seem to hold a candle to the 4080 Super. Such differences dissipate in 4K in almost all scenarios. What's the reason for it? Is it because of the memory bandwidth of the 5070 Ti which helps in huge pixel-rendering tasks?