When i was try to contact my google sheet to n8n
Google said
Access blocked: n8n.cloud has not completed the Google verification process
This may help
@x3ti the “Access blocked” screen has a small “Advanced” link at the bottom left, click that then “Go to n8n.cloud (unsafe)” to bypass it. Google shows that warning for any unverified oauth app but it still works fine, you just have to click through the consent screen manually