Revert "[Windows] FileSystem.Current.AppDataDirectory returns different path after updating to latest version - fix"

[mattleibow]

Reverts #26039

I looked into this issue some more and I see we were always putting preferences and app data in the wrong location. They were always supposed to be stored in roaming as they are supposed to travel with the app.

All the way back in 8.0.70 and 9.0.0 preview 7 we "broke" the way we stored it: https://github.com/dotnet/maui/pull/23265/files#diff-68e97c448bfa67ad3c292a6e146185895b0c2c6437fe5f361d6044327b56dc84R39

However, we actually made it all consistent - we stored the values in local storage and not roaming storage.

Then in 9.0.21 we saw it and realised that we were wrong and reverted our bug: https://github.com/dotnet/maui/pull/26039/files

However, now it is more correct, but more inconsistent and breaking to our users.

Even though technically we will be incorrect to move preferences back to local storage, it will be the way we have always done things.

Fixes #26602

[Copilot]

Copilot reviewed 1 out of 1 changed files in this pull request and generated no comments.

Comments suppressed due to low confidence (1)

src/Essentials/src/FileSystem/FileSystem.uwp.cs:39

• Reverting to using Environment.SpecialFolder.LocalApplicationData instead of Environment.SpecialFolder.ApplicationData may cause data to not roam with the user, which can lead to data inconsistency across devices.

string path = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData), AppSpecificPath, "Data");

[mattleibow]

@MartyIX FYI

[jfversluis]

@dotMorten

[PureWeen]

/backport to release/9.0.1xx-sr2

[github-actions]

Started backporting to release/9.0.1xx-sr2: https://github.com/dotnet/maui/actions/runs/12397156824

[dotMorten]

They were always supposed to be stored in roaming as they are supposed to travel with the app.

This is quite dangerous and roaming should be an opt in. Not to mention if you use encryption linked to the device/account, it won't decrypt on the other machine, and will instead keep having to recreate and overwrite the encrypted data back and forth. Or store the path to last opened file wouldn't apply to the app. There's also size restrictions on roaming data, and most importantly it's no longer supported in Win11+
https://learn.microsoft.com/en-us/windows/apps/design/app-settings/store-and-retrieve-app-data#roaming-data

If anything you might need a way in the settings API to specify where you want it to go, so you can control it (which seem moot since the support is going away), but until that happens IMHO it should default to local.