Since you've already confirmed the account is an adult account and not part of a Microsoft Family group, and you've already tried the common Family Safety reset steps, could you post the screenshot you mentioned (with any personal information redacted)?
The exact wording of the popup is important because different Microsoft components can trigger similar Family Safety prompts. Knowing whether it is coming from Family Safety itself, Microsoft Store, Xbox services, or another Windows component will help narrow down the cause.
Also, please let us know:
- Whether you're signed into Windows with a Microsoft account or a local account.
- Whether the popup appears under a specific user profile or all user profiles on the PC.
Since you've already tried the standard Family Safety troubleshooting, the screenshot and these details will likely be more useful than repeating the same reset steps.