No caso, entendi que a cora de 512mb foi excedida, foi isso mesmo, pois minha app mostra o erro:
2021-02-17T10:47:25.022314+00:00 heroku[web.1]: Process running mem=606M(118.5%)
2021-02-17T10:47:25.027279+00:00 heroku[web.1]: Error R14 (Memory quota exceeded)
2021-02-17T10:47:43.235039+00:00 heroku[web.1]: Process running mem=606M(118.5%)
2021-02-17T10:47:43.236922+00:00 heroku[web.1]: Error R14 (Memory quota exceeded)
2021-02-17T10:47:54.519379+00:00 heroku[web.1]: Error R10 (Boot timeout) -> Web process failed to bind to $PORT within 60 seconds of launch
2021-02-17T10:47:54.566602+00:00 heroku[web.1]: Stopping process with SIGKILL
2021-02-17T10:47:54.712999+00:00 heroku[web.1]: Process exited with status 137
2021-02-17T10:47:54.771982+00:00 heroku[web.1]: State changed from starting to crashed
2021-02-17T10:47:56.854509+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/topicos" host=springboot-rest-forum.herokuapp.com request_id=f6aea30f-2e8f-47f4-9870-c07cb732daf6 fwd="187.26.97.44" dyno= connect= service= status=503 bytes= protocol=https
