https://wccftech.com/how-to/small-window-opens-for-windows-insiders-to-switch-channels-how-to/

Microsoft has finally started to deliver new Windows 11 builds from the upcoming update to Windows Insiders signed up with the Beta Channel. Today's Build 22581 is being flighted to Windows Insiders in the Beta Channel along with the Dev Channel Insiders.

When this happens, Microsoft opens up a small window for Insiders to switch their channels. "Now that the Dev and Beta Channels are receiving the same builds, the limited window has opened for Insiders to switch channels if desired," the Windows development team wrote. "The time is now for you to make sure you’re in the channel you want to be going forward!"