Updated my node version from node 14.16.0 to node 16.0.0.
const { RedisPubSub } = require('graphql-redis-subscriptions/dist/redis-pubsub');
export const pubSub = new RedisPubSub({
publisher: new Redis(readOptions),
subscriber: new Redis(readOptions),
})
The pubSub.publish stopped working. Working fine with Node 14.16.0