Google requires every app to carry an accurate content rating from the International Age Rating Coalition (IARC) questionnaire — understating violence, sexual content, gambling elements, or user-generated content exposure to get a lower/more marketable rating is a violation.
Commonly caused by answering the ratings questionnaire before a later update adds mature content (chat, violence, gambling mechanics) without ever re-submitting the questionnaire to reflect the change.
"Your app's content rating does not accurately reflect its content. Please complete the ratings questionnaire again to reflect your app's current content, per the Content Ratings policy."