There was the halving in May. In every four years, the block-reward for the new Bitcoin blocks get to cut, to half of the previously. In 2020 May, after halving immediately, the miners get only half of the revenue, as the day before. But in the numbers of Glassnode, you can see, the profit is almost the same lately, thanks to the current bull run. What can’t know yet, it is, from this revenue, how much are the fees exactly?
Mining needs resources, and mining, like a business, need a serious amount of investment, and cash flow, due to the expenses. For many miners, the hodl doesn’t fit their needs. They simply have to sell their newly mined coins to cover the operation costs.