The 1920 x 1080 pixels size is not ideal for a Facebook post.
Here are the sizes for Facebook feed photos:
Horizontal image: Optimal size of 1080 x 608 pixels (aspect ratio: 1.91:1)
Square image: Optimzal size of 1080 x 1080 pixels (aspect ratio: 1:1)
Vertical image: Optimal size of 1080 x 1350 pixels (aspect ratio: 4:5)