Make sure that the tool complies with GDPR and has accompanying information to inform the users:
Write a sentence with links on the login dialog to explain that we store only the "sub" field in the Google Identity API to retrieve labeling data/statistics for a certain user, and it contains no personal information. If users sign-in, they will have access to the achievement and records.
Set most of the gtag consent mode to the "denied" state to comply with GDPR. Only enable the "security_storage" since it is necessary for security features.
Make sure that the tool complies with GDPR and has accompanying information to inform the users: