Solved: SharePoint 2019 ERR_HTTP2_PROTOCOL_ERROR 

1. Navigate to the registry key 2.HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\HTTP\Parameters.
2. Add 2 new REG_DWORD values, EnableHttp2Tls and EnableHttp2Cleartext, to this registry key.
3. Set both values to 0.
4. Reboot the server 

refer to https://stackoverflow.com/questions/67747270/reactjs-neterr-http2-protocol-error-200-with-netcore-in-https/67767129#67767129