Hi @Petr Kasnal , are you asking on how to retrieve the groups that the current user is in? I would use the Graph API for this.
https://graph.microsoft.com/v1.0/me/memberOf
You can take the user from the JWT and then run the Graph query on that user. Please let me know if you have any questions!
If this answer helped you please mark it as "Verified" so other users can reference it.
Thank you,
James