After having authorized the app with oAuth2 and acquiring permissions for requested scopes, I still get a screen asking if I grant the app permission to Have offline access, each time I try to login with Google oAuth2. Isn't it something that shouldn't appear again, once I grant it permission to have it?
This prompt could come because of two parameters,
make sure you have set access_type to 'online' and apporoval_prompt to 'auto'
$client->setAccessType('online');
$client->setApprovalPrompt('auto') ;