vpn traffic isnt directly hidden, but it can be helped along.
youd need to encapsulate your vpn traffic in a different protocol, make sure you shape your traffic to expected values for that protocol and then avoid known vpn endpoints.
Neither. They detect new secure connections outside of Russia. Then connect to the same host and check if it has a VPN handshake. If it does - the host gets blocked. No need for DPI or anything complex and 100% ban rate.