Welcome Mirabel,
Thank you for reaching out to Microsoft Q&A forum.
Since this is your personal home PC and the message can appear even shortly after Windows starts, let's try to identify the app that is repeatedly triggering it rather than checking the Store for updates again.
- The next time the message appears, select Learn more about Smart App Control if possible. Then open Windows Security > Virus & threat protection > Protection history and check whether there is a recent Smart App Control or Blocked app entry. Please let me know the app/file name shown there.
- If an app is identified, open Settings > Apps > Installed apps, find that app, select Advanced options if available, and try Repair first.
- If Repair does not help, return to the same page and use Reset. Please note that resetting an app may remove that app's locally stored settings or data.
Looking forward to your update.