If you are using an in-browser Ethereum wallet (e.g. Metamask, Brave, Parity) then any website can detect if you are an Ethereum user. I wouldn't be surprised if some advertisers are already collecting this information.

If you are using an in-browser Ethereum wallet (e.g. Metamask, Brave, Parity) then any website can detect if you are an Ethereum user. I wouldn't be surprised if some advertisers are already collecting this information.