While the amount of Bitcoin in miners' hands continues to decrease, its value against the dollar is increasing.
Miners' Bitcoin Reserves:
In 2019, Bitcoin miners held approximately 2.9 million Bitcoin.This number has been steadily decreasing since then. As of today, miners hold approximately 2 million Bitcoin (source: intotheblock).
Value of Miners' Bitcoin Reserves:
In nominal terms, the amount of BTC they hold has decreased. However, in terms of value, it has reached the 2021 level again.
To illustrate:
On April 5, 2021, miners held 2.37 million Bitcoin, worth approximately $142 billion. As of today, miners hold approximately 2 million Bitcoin (worth approximately $129 billion).
Conclusion:
After the halving, we can expect miners' reserves to decrease (also to meet the increasing demand).
However, this is not a scary situation. I expect the dollar value of Bitcoin in miners' hands to exceed the previous all-time high in the near future. The reason for this is that the "realised price" (approximately the cost) of Bitcoin will increase after the halving. Overall, this is a data point that we should regularly check to better understand the bull cycle.