Stop Store apps running in the background (policy) — via Microsoft Learn

Group Policy

Open gpedit.msc (Pro, Enterprise and Education only) and go to:

Computer Configuration > Administrative Templates > Windows Components > App Privacy > Let Windows apps run in the background (Enabled, Default for all apps: Force Deny)

Registry equivalent

Double-click a .reg file and confirm to merge it. Right-click → Edit first if you want to read it, which is always a good idea with any .reg file from the internet.

Apply

Windows Registry Editor Version 5.00

; Oddbyte.Me: Stop Store apps running in the background (policy)

[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\AppPrivacy]
"LetAppsRunInBackground"=dword:00000002

Undo

Windows Registry Editor Version 5.00

; Oddbyte.Me: undo Stop Store apps running in the background (policy)

[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\AppPrivacy]
"LetAppsRunInBackground"=-

Same thing from a command prompt

Run in an administrator Command Prompt or Terminal.

reg add "HKLM\SOFTWARE\Policies\Microsoft\Windows\AppPrivacy" /v "LetAppsRunInBackground" /t REG_DWORD /d 2 /f

Undo:

reg delete "HKLM\SOFTWARE\Policies\Microsoft\Windows\AppPrivacy" /v "LetAppsRunInBackground" /f

Microsoft warns that Search and some built-in apps may not work as expected with Force Deny. Apps already open need restarting for the policy to apply. The policy also supports per-app allow/deny lists by Package Family Name.