> Would bitcoin mining be better if it would use clean energy?
No, Bitcoin mining should not exist. It serves no demonstrable net-positive value to society.
> I think you really are mixing two things here
I'm not, you seem to be confused. Energy production is produced only because it is economically viable to do so. Bitcoin makes it economically viable to produce most forms of energy, regardless of that specific source's environmental impact. This is harmful consumption of energy. Like leaving the lights on when you're not home, simply because you don't care. Bitcoin is not indifferent, its core function is to increase energy usage. Some people would have you believe Bitcoin's core value is its use as a currency. Its value is as infrastructure that wastes energy for profit, and the collective buy-in and infrastructure created to ensure it remains a store of value.
You could maybe argue this is worth it, if there were absolutely no other way to do it. But there is, and it works much better. Central banking is strictly superior to cryptocurrency for most reasons that the average person cares about. If you don't agree, that's irrelevant, because you're an outlier. Most people want cheap transactional costs, fast transactions, and for their money to have stable value. They couldn't care for a second if the transaction is cryptographically secure as long as it's reasonably insured.