Summary:
In the UWP version, Minecraft and Minecraft Preview each stored their local cached data in separate LocalState folders under AppData\Local\Packages\Microsoft.MinecraftUWP. After the GDK update, these have been replaced by a single shared minecraftpe folder located in AppData\Local\Temp\minecraftpe.
Because both apps now share this cache directory, it is no longer possible to clear the cache for only one of them.
Steps to Reproduce:
Navigate to AppData\Local\Temp\minecraftpe and delete all files.
Launch Minecraft. The minecraftpe directory should regenerate all required folders.
Exit Minecraft.
Delete all files in AppData\Local\Temp\minecraftpe once again.
Launch Minecraft Preview. The minecraftpe directory should regenerate all required folders.
Observed Results:
Minecraft and Minecraft Preview are sharing the same cache folder.
Expected Results:
Minecraft and Minecraft Preview should maintain separate cache folders, as they did previously.
Comments 2
Please avoid posting comments unrelated to this issue. For your information, world saves and add-ons are stored in an accessible folder: AppData/Roaming/Minecraft Bedrock/Users. This information is noted in the 1.21.120 changelog and can also be found with a quick online search.
Your add-ons failing to install are not caused by the location where worlds and add-ons are stored. Without more details, it is difficult to say exactly what the issue is, but I suspect you are encountering MCPE-227874.
World save folders and add-ons should be located in an ACCESSIBLE FOLDER. Many add-ons fail to install because the folder is located in the middle of nowhere. The installation folder needs to be in an accessible location. It should be in Documents, like most regular games do.