What type of sealer are you using?
Leathered finishes are not polished and usually don't have a shine. The pours of the stone are more open and can absorb more.

I probably didn't explain well. They put a sealant on , and there are streaks and it appears that one area absorbed more and another less. It isn't even.

1) why does this need any sealant? the fabricators should have delivered it in final form, and they should know how to handle a leathered finish if they sell it.

2) I can't see how to fix it now, since most counter fixes involve buffing, which will ruin the finish you chose and probably paid extra for.

I feel like your only choices are to seal everywhere until you get a thick layer that's shiny everywhere (thus not leathered in effect) or to let it go and hope that normal wear will sort of de-shine the strangely shiny zones. does your fabricator have advice, or is all this sealing somehow being done by somebody like your general contractor who shouldn't be messing with the counters?

What sealer was used? Different sealers do different things. Knowing what type of sealer could explain why this is happening.

Leather finish countertops are not shiny.

Chances can be that you might not be wiping up 100% of the water. What you can do is pour a drop of water, maybe a few drops to make a dime size spot. If it sits on tops of the stone, it is properly sealed and you wont have a problem.

The look and texture of leather granite is different from polished so expectations cannot be the same. It is more porous, could dry a little slow so it keeps the moisture and that is when you can see the dark spot, but it will fade away once completely dry. Try the water spot test, pour the drops and post a photo of how it sits, that will help.

Either the sealer was left on pooled up in that spot and left to dry (clean with acetone and a razor blade and re seal) or antique brown varies in grain size from a tight grain to a very big grain. The big grain can get a colourful reflection like a fish scale. It's possible this fish scale with a leather finish is giving a funky look in comparison with the rest of the top (Nothing can be done it's part of the stone) A picture would be nice.