VPN apps on Google Play are under intense scrutiny. Using VpnService without being a real VPN, or being a VPN without the required disclosures, both lead to rejection. Here's what Google actually requires.
What Apple said
“Your app uses the VpnService API but does not meet the requirements for VPN apps on Google Play. Apps using VpnService must be a legitimate VPN application, must clearly disclose what network traffic is routed through the VPN, and must not use VPN capabilities for advertising, data collection, or purposes other than providing VPN functionality.”
Google Play has strict rules for VpnService API usage because it can be abused to intercept traffic. Legitimate VPN apps can publish, but they must clearly disclose that they route network traffic, what the traffic is used for, and must not collect or use the traffic data for any purpose other than providing VPN service. Non-VPN apps that use VpnService for other purposes (like parental controls or ad blocking) face heavy scrutiny.
While you're at it — Apple also requires these pages for every app.
Fix this rejection, then make sure you're covered on the compliance side too. Apple requires every app to link to a hosted Privacy Policy, Terms of Service, Support page, and Data Deletion page. No link means another rejection — just for a different reason.