Microsoft is beginning what will be a very long and drawn-out process of no longer supporting 32-bit versions of Windows 10. Beginning with Windows 10 version 2004, which is already available to OEMs and developers, the company is no longer offering a 32-bit version of the OS to OEMs for new PCs. The change is indicated on the Minimum Hardware Requirements documentation.
To be clear, this change does not affect existing PCs, and Microsoft says that it's still committed to offering 32-bit builds in other channels. That means that you can still buy a retail copy of Windows 10 and use it to get 32-bit media. But the writing is on the wall at this point. Eventually, 32-bit CPUs won't be supported by chip vendors anymore, and these devices will just go away at some point. With today's change, OEMs can't make new ones.
That's if they could find the silicon for it at all. Any modern PC that you can buy has a 64-bit CPU, and the simple reason for making this change is because there's almost no demand for 32-bit PCs. This news is more notable because it's the beginning of a long road toward them not existing anymore.
Last year with Windows 10 version 1903, Microsoft increased the minimum amount of storage that a new Windows 10 PC can have. Rather than being 16GB on 32-bit devices and 20GB on 64-bit devices, it's now 32GB across the board. It would seem that doubling the required storage and putting it on par with 64-bit PCs might have been a subtle step toward this.
If you have a 32-bit PC, there's nothing to worry about, and there likely won't be. These PCs will likely die out on their regular support timelines, unless Microsoft changes up the policy at some point.