Firstly, are you receiving any of the logs? Is there a specific reason you're using the realtime-js lib over the supabase-js lib? For example, this

update

example I use in a prod environment without a problem:

js
SupabaseClient.from(`my_table:my_column=eq.some_value`)
  .on("UPDATE", (payload) => {
    console.log("🔥 Received update via subscription from Supabase");
  })
  .subscribe(result => {
    if (result !== "SUBSCRIBED") {
      console.log(`❌ Error subscribing: ${result}.`);
    } else {
      console.log(`🔥 Opened subscription`);
    }
  });

Thanks for the attention. The problem was that my publication supabase_realtime existed but was not attached to any tables. After I dropped it and recreated it with "for all tables" it started working and showed under "select * from pg_publication_tables;"