I think I fixed my problem with this message. I had set my home assistant server to a fixed IP address in the router, in “addons, backups and supervisor” > “system” > IP Address it was pointing to “DHCP”. When I changed it to “Fixed IP” this resolved the annoying messages. Thanks @mousawm for giving me a clue where to look.
10/02/22 - Update dammit the issue is back so no it wasn’t a fix. Sigh 
I have been getting this error for about a month now and nothing has been changed. It just showed up and I can’t to the life of me figure out what is wrong. I have a static IP on the HA server which is a direct install to an Intel NUC. The system I am accessing from has a static IP and been the same since I built it over a year ago. No configuration changes have been made in over six months. Just the updates is all that has changed over the last few months, then it appeared.
I recently found the culprit of this error on my system to be a tablet running the HA app. I logged it out, then back in and haven’t had the error again since.
What fixed it for me was turning off “Can only log in from the local network” option in “Settings” > “People” > (person from whose phone the login attempt was coming from):
hi this code work fine for me it slove my problem… thanks
Been having this issue for the past few months, finally just noticed it was triggered when I tried (and failed) to log in via the Home Assistant Cloud ui.nabu.casa domain.
Taking @Neovision 's advice, I went looking at users and realized that the default Home Assistant Cloud user in my system is set up for “Can only log in from the local network”, a setting that can’t be changed for it.
So it seems like HAC is running authentication through localhost (127.0.0.1), which, if it’s not in the list of “trusted_proxies”, triggers the notification.
You didn’t find a solution then? This seems to be my issue too…
Any updates on this? I think I am also having this issue.
The solution is simple: uncheck “use HA cloud” under the server login options in the app. It will revert to connecting locally over ip, instead of trying to pass through the NGINX proxy where the authentication is invalid, because it sees you trying to login from a non-local IP address
Unchecking that option solved it for me too
