Has there been a recent app-scripts change that stops unsubscribing Observables?

I just spent some time chasing a “bug” and it appears as though what was happening was that if I saved code, partially restarting Ionic Serve, my program would begin execution again, but with the previous Observable subscriptions cached and still alive. If I close the browser and restart Ionic Serve, I don’t have the bug anymore.

So my question: has this always been true, and I just never wrote code before that ran into it? Or is app-scripts handling subscriptions differently now?

Sample way to recreate issue: page subscribes to some Observable, then hits a runtime error. I fix the error, save the new code and the program continues, resubscribing to the same Observable while keeping the previous subscription also.