I'm reporting this as on 20/09/20. I have a Galaxy Tab S6 and recently less than one week ago the Facebook app has not displayed properly on any of it's pages in landscape mode. There are wide grey bars down each side of the screen. The app used to fill the screen previously. Also, pictures that friends post are 'zoomed in', so they don't display correctly until you actually tap on the post to open it. Seems to be a Facebook issue, but is only happening on my Samsung tablet. I have Samsung and OnePlus phones and they display Facebook fine. I have deleted the cache to no avail and reinstalled the app, which initially seemed to fix the error, but it has returned after closing and opening the app for a second time. Hopefully, Samsung and Facebook can sort this out quickly as it is ruining the Facebook experience.
Have you found a solution? This is frustrating, Just bought this tablet.