The Facebook Groups API is deprecated in v19 and was removed from all versions. This deprecation included all Permissions (publish_to_groups, groups_access_member_info) and Reviewable Features (Groups API) associated with the Facebook Groups API. https://developers.facebook.com/blog/post/2024/01/23/introducing-facebook-graph-and-marketing-api-v19/

I can't find a way to post to the Facebook group via Graph API