Microsoft has updated the release notes for the recently shipped build 26052 to mention quite a severe bug that can wipe a lot of data on your computer without any warning. As it turned out, rolling back to previous Dev or Canary builds results in the operating system damaging Dev Drives and causing data loss. Therefore, if you plan to go back, back up the contents of your Dev Drives before proceeding. Data on other drives and partitions should remain intact.
Microsoft acknowledged the problem and published a heads-up in the official Windows Insider account on X:
We added a very important known issue for Dev Drive users on Build 26052: Insiders who have Dev Drives and might need to rollback will need to back up their Dev Drives BEFORE rolling back as rolling back will cause Dev Drives to break and data on them to be lost. ^BLB https://t.co/IZTK8PmspG— Windows Insider Program (@windowsinsider) February 9, 2024
Sadly, some users learned about the bug the hard way before Microsoft posted an update, which is yet another proof of why running Windows preview builds on a primary device is not a very good idea. Hard-hitting bugs and critical errors are expected in pre-release software, and they sometimes slip under the radar.
In addition to problems with Dev Drives, Microsoft added another known issue in build 26052. It is not as severe as the one wiping your partitions, but still, beware since it will crash the Settings app:
A Display Connection section is incorrectly showing up under Settings > System > Display > Graphics that when clicked, will crash Settings. This section will be removed in a future flight.
Other bugs in Windows 11 build 26052 include green screens of death when playing popular games, issues with playing streaming content in the Microsoft Store apps, and frequent black screens (you can resolve it by restarting the graphics with the Win + Ctrl + Shift + B shortcut). It's pretty buggy stuff, so it is better to check out build 26052 on a spare computer or inside a VM.