How would I diagnose an ssl.WRONG_VERSION_NUMBER error in python3

I am using python3 ssl to connect via web sockets to an nginx server. According to my code below, I should be connecting via TLSv1_1.3 since I not using 1, 1.1, or 1.2. My ssl (OpenSSL 1.1.1h 22 Sep 2020) supports TLSv1.3.

    sslCon=None
    if self.server.startswith("wss"):
        sslCon=ssl.SSLContext(ssl.PROTOCOL_TLS)
        sslCon.options |= (
            ssl.OP_NO_TLSv1 | ssl.OP_NO_TLSv1_1 | ssl.OP_NO_TLSv1_2
        )
    self.conn = await websockets.connect(self.server, ssl=sslCon)

My NGINX config specifies TLSv1.3, but when I observer the connection over Wireshark, I see the following. Any ideas to how to diagnose this further?

Frame 3172: 308 bytes on wire (2464 bits), 308 bytes captured (2464 bits) on interface en0, id 0
Ethernet II, Src: Apple_62:32:d8 (XX:XX:XX:XX:XX:XX), Dst: Cisco_9f:f2:8f (00:00:0c:9f:f2:8f)
Internet Protocol Version 4, Src: XXX.XXX.XXX.XXX, Dst: XXX.XXX.XXX.XXX
Transmission Control Protocol, Src Port: 62035, Dst Port: 8189, Seq: 1, Ack: 1, Len: 242
Transport Layer Security
    TLSv1 Record Layer: Handshake Protocol: Client Hello
        Content Type: Handshake (22)
        Version: TLS 1.0 (0x0301)
        Length: 237
        Handshake Protocol: Client Hello
            Handshake Type: Client Hello (1)
            Length: 233
            Version: TLS 1.2 (0x0303)
            Random: dccd34397b86bac156d3ae39483a268ed3536ef09a3557c3…
            Session ID Length: 32
            Session ID: ea577122c909b7c78e20dbb5f982a7be94169fac8f51886f…
            Cipher Suites Length: 8
            Cipher Suites (4 suites)
            Compression Methods Length: 1
            Compression Methods (1 method)
            Extensions Length: 152
            Extension: server_name (len=23)
            Extension: ec_point_formats (len=4)
            Extension: supported_groups (len=12)
            Extension: session_ticket (len=0)
            Extension: encrypt_then_mac (len=0)
            Extension: extended_master_secret (len=0)
            Extension: signature_algorithms (len=30)
            Extension: supported_versions (len=3)
            Extension: psk_key_exchange_modes (len=2)
            Extension: key_share (len=38)