System folders, such as WindowsApps, are locked down with TrustedInstaller level access. That's controlled by a service (TrustedInstaller is not an account). This is done to protect the OS from malware. If you could easily change those permissions, then so could malware. It's not a bug, it's a feature.
Normally, there's no reason to make changes in such folders and messing with the permissions is asking for trouble.
If you must make a change to a protected folder (e.g. to mod a game from the Microsoft store) then it's best to leave the permissions alone and instead use a tool that gives you TrustedInstaller access, such as PowerRun, AdvancedRun, or my free Right-Click Tools.