Facebook looks at the overall engagement of pages within a 24 hour period. If the engagement is low (e.g. few clicks, shares, and comments), Facebook might restrict the number of posts that can be published until engagement levels increase. If your page is restricted, posts in Buffer will fail to publish and you'll see the following error.
It looks like we're bumping into a few Facebook page limits.
To help resolve this, we recommend reducing the number of posts that you're publishing, so you don't reach the request limit. Try sharing just one post every 24 hours to begin with. We also recommend that you try to increase the overall engagement on your page.