Looks like there was a problem with a react app's reloading websocket thingie. So I decided to test.
Here is a random react app that I decied to try: https://github.com/ahfarmer/calculator
$ npm start
Without an upgrade config:
[2020-02-25 01:13:26.243][4407][debug][http] [source/common/http/conn_manager_impl.cc:731] [C8][S17729359102081406356] request headers complete (end_stream=false):