How to debug websocket_api.http.connection.xxxx errors in the log

After having disabled websocket_api: in my setup, and the corresponding

sensor:
  - platform: websocket_api

I still see

2019-09-02 22:39:48 INFO (MainThread) [homeassistant.components.websocket_api.http.connection.1826258480] Connection closed by client
2019-09-02 22:42:39 INFO (MainThread) [homeassistant.components.websocket_api.http.connection.1838240368] Connection closed by client

How can we debug this? I’d really like to know which integration is causing this, what it means for the setup, and what the numbers point to at the end.
thanks for having a look.

would love to know aswell