[Aissen]

They even have a nice comment explaining the heuristic: https://github.com/wireshark/wireshark/blob/ef9c79ae81b00a63...

     * Heuristics to detect the WireGuard protocol:
     * - The first byte must be one of the valid four messages.
     * - The total packet length depends on the message type, and is fixed for
     *   three of them. The Data type has a minimum length however.
     * - The next three bytes are reserved and zero in the official protocol.
     *   Cloudflare's implementation however uses this field for load balancing
     *   purposes, so this condition is not checked here for most messages.
     *   It is checked for data messages to avoid false positives.