I've searched and searched, and all I can find for the maximum size of a picture on Facebook is the (old) 2048x2048 pixel maximum.
However, I just downloaded a picture posted to a Facebook Group, that was surprisingly 4041x1037. (January 20, 2020)
I've heard rumblings about Facebook doing some more changes, so this seems to be true.
Does anyone know what the new maximum pixel dimensions are? Thanks.