And not nearly enough because no human activity can realistically cover some 100-200 million years of geological processes.
In most places they just want to flood the hole. These artificial lakes then become a toxic hole because the Iron-Sulfide exposed during mining oxidizes into Iron-Sulfate, leading to these lakes being diluted Sulphuric Acid for decades if not centuries.
Also the groundwater cannot recover a century of pumping it out in less than multiple centuries. Then the water used for flooding is diverted from rivers, which already are running low in these region and the artificial lakes are evaporating a lot of water, further drying things out.
Oh and of course the holes tend to be sold to some smaller private investors by the end of their lifetime who do not have nearly enough funds to be held liable for renaturization. So the tax payers will be looking at dozens if not hundreds of billions of damages to front over the next centuries while the profiteers moved their money elsewhere.