My mistake. I was thinking it was due LinkedIn to force the usage of Oauth v2.
It is in fact a change on my configuration to not allow account creation:
authpreventaccountcreation was checked - now it is back to the default and it works as intended - people can use their LinkedIn account to have access to Moodle without the need to request the account creation in Moodle.
I wish I had check this before...
