How to prevent Screen Time restrictions from being reset on my child's iPhone?

I have certain restrictions in place for my child's iPhone for the following:

• Content & Privacy Restrictions > App Store, Media, Web & Games > WEB CONTENT

I set WEB CONTENT to "Limit Adult Websites" and fill in a list of sites under "NEVER ALLOW".

Additionally, I configure ALLOWED MEDIA SERVICES CONTENT to limit acccess only to age appropriate material for Movies, TV shows, Apps, Books, etc.

Also under Content & Privacy Restrictions > ALLOW CHANGES:

I set various options to "Don't Allow".

After a while, when I go in to Screen Time to review configurations and restrictions, I find that the above restrictions I have set up ARE ALL GONE and it's all been reset to maximum access, everything allowed.

Is there some sort of bug or glitch, or has my child figured out how to change/remove these restrictions? Some anti-Screen Time app or program that parents don't know about?

[Re-Titled by Moderator]