I have a RTX 3070 Gigabyte Gaming OC 8GB, but it sits inside a relatively hot server, so I expect some hashes might be lost just there.
But it's important to compare with the same tools, maybe nicehash calculates hasrates differently as well. A fair comparison would be using nsfminer for windows and the one in linux/docker container, and then use nvidia-smi on both windows and linux to determine power usage (maybe also nvidia-smi shows the same clocks as well across platforms?).