NestJS GraphQL subscriptions not working with `graphql-ws`

I'm trying to upgrade our NestJS GraphQL subscriptions server to utilize graphql-ws rather than the current subscriptions-transport-ws (as suggested by the NestJS documentation). I upgraded the NestJS version to

 "@nestjs/core": "^8.0.6", "@nestjs/graphql": "^9.0.4", "@nestjs/platform-express": "^8.0.6", "graphql": "^15.5.3", "graphql-tools": "^8.2.0", "apollo-server-express": "^3.3.0", 

And after, I added the subscriptions option to the App.Module:

 GraphQLModule.forRoot({ autoSchemaFile: true, sortSchema: true, playground: true, installSubscriptionHandlers: true, subscriptions: { 'graphql-ws': true }, }), 

However when I subscribe (in playground) to a previously working subscription, I get:

{ "error": "Could not connect to websocket endpoint ws://localhost:8880/graphql. Please check if the endpoint url is correct." } 

And in the console I get:

WebSocket protocol error occured. It was most likely caused due to an unsupported subprotocol "graphql-ws" requested by the client. graphql-ws implements exclusively the "graphql-transport-ws" subprotocol, please make sure that the client implements it too. 

Things I have tried:

• Adding the graphql-ws package
• Upgrading the NestJS version again
• Removing the installSubscriptionHandlers option from config
• Setting graphql-ws configs instead of passing true
• Using the WebSocket Test Client Google Chrome extension instead of Playground

But none have worked. Sorry for the long post. How can I fix this?