Minecraft Preview is the new standalone beta application for Bedrock

pcgamer.com:

Beta versions of Minecraft Bedrock for Windows now have their very own standalone application, Minecraft Preview, free for Minecraft owners and Xbox Game Pass subscribers. Change may be scary, but this one honestly sounds like a real improvement over the headaches that the old Minecraft beta process has always caused me.

As of today, you can download Minecraft Preview from the Xbox store or through the Xbox app for Windows. You'll already own the app if your account has a copy of Minecraft Bedrock or a Game Pass subscription. As we get closer to the Minecraft 1.19 Wild Update later this year, this is how Mojang will let players on Minecraft Bedrock continue trying out new features and creatures like those frogs and mangrove trees.

Importantly, Minecraft Preview is a totally separate application from Bedrock. So your game saves, marketplace items, and achievements aren't available in Minecraft Preview—nor is multiplayer. 

Minecraft update: What's new?Minecraft skins: New looksMinecraft mods:  Beyond vanillaMinecraft shaders: SpotlightMinecraft seeds: Fresh new worldsMinecraft texture packs: PixelatedMinecraft servers: Online worlds Minecraft commands: All cheats

It also means less pain when playing the beta version, overall. Previously, Bedrock players had to download the Xbox Insider Hub, opt into the Minecraft Beta program, and then their version of Minecraft Bedrock would be switched to the beta version. Switching back and forth was an absolute hassle, sometimes requiring me to re-download the entire game through the Microsoft store for the transition between versions to stick. Unlike Minecraft Java, Bedrock has never allowed multiple version installations. So I personally won't be mourning the Bedrock and Beta