How does one turn crypto back into energy?
Even if we assume (which is definitely not a safe assumption) that burning all that oil in the first place to mine the coins produces less carbon than the overall reduction caused by the increase in demand for solar panels and subsequent increase in their production and deployment (because just buying solar panels that were already being produced and going to be deployed by someone does not reduce the overall carbon load of the planet)...
That requires the miners to sink all their profits into buying solar panels, rather than, y'know, making money for themselves, which is the reason they're mining cryptocurrency in the first place.
I did not check this but Michael Saylor claims that over 40% of mining is done using renewable energy. Considering solar power by itself is a good investment last time I checked ( around 13% ROI depending on your local energy price) then that number will probably increase as it just makes business sense to do it.
I could use money I earned from selling power generated by a coal plant to buy solar panels. That doesn't make the coal plant produce twice the energy.