After save as Preserved input format.
That photo can not share to Facebook because it is .png format.
- Facebook post image size.
You can upload files in any of the following formats: JPEG, BMP, PNG, GIF, or TIFF. If you’re uploading a PNG file, it’s best to keep the file size below 1MB. PNG files larger than 1MB may appear pixelated.
Of course FB accepts PNG files. But I don’t advise doing that because FB converts them to JPG and makes them a massacre. I recommend converting the file to JPG format yourself in around 95% quality, for example with XnView, where you have full control over the compression parameters.
