Its a bug in WP 5.3
Please see here: https://core.trac.wordpress.org/ticket/48599 and here: https://wordpress.org/support/topic/error-after-5-3-update

We will release an update with workaround fix soon.

injektil@gmail.com wrote:

Posting to Facebook is broken for me after updating to 4.3.10

i am having the same problem.. i can not post to facebook again after i did an update, i keep getting this error
Array
(
[Warning] =>
[Error] => (#200) If posting to a group, requires app being installed in the group, and \
either publish_to_groups permission with user token, or both manage_pages \
and publish_pages permission with page token; If posting to a page, \
requires both manage_pages and publish_pages as an admin with \
sufficient administrative permission
)
Array ( [Warning] => [Error] => (#200) If posting to a group, requires app being installed in the group, and \ either publish_to_groups permission with user token, or both manage_pages \ and publish_pages permission with page token; If posting to a page, \ requires both manage_pages and publish_pages as an admin with \ sufficient administrative permission )

Just to be clear the admin has permission and also we have permission to manage page and publish to page