I can't join Among Us because it is showing You can't join games due to parental control.

Is this the only game that you're having an issue with playing online?

Also, please validate that you're managing the setting for the correct account.

That's odd, can you please go to https://account.xbox.com/settings again and then block the setting that has an arrow in this screenshot then submit, after that allow again then submit.

Restart your PC before testing it out.

Were you able to change it?

In this case, you may need to reach out to the game support. Here you go: https://www.innersloth.com/contact/

Hi, I hope you're doing great out there despite the issue that you're experiencing. I am an Independent advisor and I am here to help you in regards to your concern.

For you to manage it you can simply sign in to https://account.xbox.com/settings.

If the system detects that your account is a child account you will be redirected to a support site and if not you will be able to change it successfully.

If you were redirected to a support page, please sign in to https://account.microsoft.com/family and check if there is an organizer account linked to your account then use the organizer account so sign in to https://account.xbox.com/settings then "allow" the setting on this screenshot: