Today, Microsoft released Windows 10 Insider Preview build 21354, and alongside it, we're getting new ISO images for those that want to do a clean installation of the OS. The last time Microsoft released new Dev channel ISOs was on January 6, when it published images for Windows 10 Insider Preview build 21286.
There were, however, Beta channel ISOs released since then. In March, the company published its first ISOs for Windows 10 version 21H1. In fact, 21H1, or build 19043, is shown as being the ISOs for both the Beta and Release Preview channels. This is despite the fact that 21H1 isn't actually available in the Release Preview channel unless you're a commercial customer.
The Dev channel isn't tied to a specific release, so this is officially another prerelease build. That means that if you install this, there's no telling when you'll be able to switch off Insider Preview builds and return to production without doing a factory reset. We all expected 21H1 to be that, but instead it turned into a minor update with the build number only increasing by one.
We're now expecting the next major update to be 21H2. It's going to have some big visual changes, x64 emulation on ARM, possibly Android emulation, and more.
You can download the new ISO images here.