A request from a reverse proxy was received from

[Troon]

@erik3

I have a plain vanilla installation of Home Assistant and I only use some of the build-in integrations. I have not set up anything to use a reverse proxy, so it must be some of the core / built-in stuff which is causing this.

OK, that’s a bit different. Have you set up Nginx? Is your installation Home Assistant OS on e.g. a Pi?