If you attempt to gmail sign in from chrome, it will sign in your chrome account (https://www.mattcrampton.com/blog/sign-into-gmail-without-signing-into-google-

If you attempt to gmail sign in from chrome, it will sign in your chrome account (https://www.mattcrampton.com/blog/sign-into-gmail-without-signing-into-google-chrome/ https://www.mattcrampton.com/blog/sign-into-gmail-without-si...), which will, if you have no account on your phone, sign in your phone. Tricky little buggar that one. Still easier to avoid than rooting, but easy to get wrong by mistake.