Apache Superset PostgreSQL Query: Network address operator <<= Not Supported

I have a new instance of Apache Superset and SQL queries to PostgreSQL databases from SQLLab is working. The exception is SQL which use the <<= 'is contained within or equals' network address operator:

WITH subnets AS (
SELECT UNNEST(networks) AS subnet,
       network_owner,
       owner_country,
       provider_country,
       registrar
  FROM network_data
)
   SELECT network_owner,
          owner_country,
          provider_country,
          registrar,
          subnet,
          (2 ^ (32 - MASKLEN(subnet)) - 2) AS subnet_size,
          (
              SELECT COUNT(DISTINCT(q.ip_address))
                FROM request q
               WHERE q.ip_address <<= subnet
          ) AS num_logged,
          u.timestamp AS blocked_timestamp
     FROM subnets
LEFT JOIN ufw_blocked u ON subnet = u.blocked_address_space
 ORDER BY network_owner, subnet

This works perfectly in pgadmin4 but SQLLab seems to mistake the <<= operator for 'less than or equals' and returns the errors below:

Unable to parse SQL:
Error parsing near '<=' at line 18:37
WHERE q.ip_address <<= subnet
                     ^

DB Engine Error: This database does not allow for DDL/DML, and the query could not be parsed to confirm it is a read-only query. Please contact your administrator for more assistance
This may be triggered by:
Issue 1022 - Database does not allow data manipulation

The <<= operator is described in the PostgreSQL documentation at:

https://www.postgresql.org/docs/current/functions-net.html

Is there an alternative way of presenting this operator in Superset SQLLab?