xstate: NodeJs memory leak with interpret (xstate>=4.7.0-rc6)

Description

Occurs when using interpret.

Expected Result

After executing the request, classes using interpret will be removed from the memory by GC.

Actual Result

The memory is allocated, but not freed after the request.

Reproduction

I currently have no idea how to show a minimal working example.

Simplified application diagram:

function requestHandler(r, h) {
    ...
    new Kernel() {
        ...
        new SomeModule() {
            constructor() {
                ...
                this.interpreter = interpret(
                    Machine(machineConfig)
                );
    
                this.interpreter.onTransition(nextState => {
                    this.updateState(nextState);
                });
                ...
            }

            ...
    
            afterLoad(pageCtx) {
                ...
                this.interpreter.start(this.initialState);
                ...
            }
    
            beforeUnload() {
                ...
                this.interpreter.stop();
                ...
            }
    
            ...
    
            @action
            private updateState(nextState) {
                this.stateValue = nextState.value;
            }

        ...

        }
    }
    ...
    // render React to string
    // serialize App state

    return h.response('html page with serialized App state (data + xstate.StateNode)');
}

Additional context

A memory leak is not observed in version 4.7.0-rc5, but appears in 4.7.0-rc6

There are no tags for these versions, so I could not provide a link to the changes.

In tests, I used this version list: https://www.npmjs.com/package/xstate?activeTab=versions

• xstate >= 4.7.0-rc6
• node >= 12.13.0