Users unable to login with Discourse Connect

I can see why the SSO login is failing.

Verbose SSO log: Nonce is incorrect, was generated in a different browser session, or has expired add_groups: admin: moderator: avatar_force_update: avatar_url: bio: card_background_url: email

So, we have embedded the discourse inside our web application using iframe. I don’t see why this could be a problem since we are using this set up for the last 18 months.

What do you think could be the issue, because nothing has changed?