Facebook website thumbnail Sizes

Hello,

I have been trying to figure this out for a couple of hours now.

I saw the recommended sizes on google and on facebook...

and I have setup the images to 1200 x 630

but it still shows a "SMALL" thumb on mobile...

what is weird is that it fb debug tool... it displays A BIG THUMB...

and on desktop it displays a BIG THUMB...

but on mobile... it displays a small thumb...

so here I am asking you guys...

What do you guys think about it?

What should I do to fix it?