The user must be an administrator of the page in order to impersonate it

I am getting this error:
FacebookResponseException in FacebookResponseException.php line 106: The user must be an administrator of the page in order to impersonate it.

The admin has been changed and the website has a new developer now (me). The feed worked before and I have no idea what else to try... This is everything that has changed or I did to the code:

1. I am the administrator (one of 4) of the facebook page with my personal profile.
2. And I am also the owner of the facebook developers app.
3. I have only changed the .env credentials (the faceboook_app_id and facebook_app_secret).

Any ideas on what could fix this? I found this similar problem, but I only need to get some of the last posts and the feed, so I dont need to post to the page (like the other question).

via Chebli Mohamed