It seems that a workaround to the artificially enforced hashrate limiter for the Nvidia GeForce RTX 3060 GPUs mining Ethereum has been discovered and it is pretty simple apparently. You just need to use the developer driver version 470.05 where there is apparently no hashrate limiting being applied, unlike with the regular GeForce video driver that you would normally download for these video cards. This has been reported by some users and we can confirm that it is indeed working and you can get the full mining hashrate for Ethereum with this driver.
We are getting 47 MH/s Ethash mining hashrate using the Nvidia developer driver version 470.05 with PhoenixMiner mining Ethereum, with the following settings in MSI Afterburner: 70% TDP, -500 MHz GPU, +1000 MHz video memory. You can check what performance does a Asus ROG Strix GeForce RTX 3060 OC Edition manage to provide you with with the limited hashrate regular drivers, though the limit is not for all crypto algorithms, but for memory-intensive ones such as Ethash and VertHash for instance.
The drawback is that the Nvidia developer driver version 470.05 does require you to register on the Nvidia website as developer and is currently still available for Windows only, but hey, it works and you get the full mining hashrate mining Ethereum and other algorithms such as Verthash used by Vertcoin that apparently also suffered from the hashrate limitation introduced by Nvidia for the RTX 3060. For VTC mining with the above settings the hashrate we are getting is around 810 KH/s instead of the reduced in half sub-400 with the regular driver.