Casting from Kodi to a Chromecast or UPnP device can use more phone battery when Symfonium has to relay the audio through the phone.
Why the phone relays the audio
Section titled “Why the phone relays the audio”If Kodi requires authentication and the playback device cannot handle it directly, Symfonium automatically acts as a proxy. The audio travels from Kodi to your phone, then from your phone to the playback device. This keeps the phone transferring audio during playback and can increase battery use.
What to check
Section titled “What to check”In the casting settings, Proxy via Symfonium can also force audio through the phone. Turning that option off does not prevent automatic proxying when authentication requires it. The Kodi configuration guide explains the server connection and authentication settings.
If you need help with battery use, gather logs and open an issue. Include the media provider, playback device, whether you were casting, and how long playback ran. These details also help investigate battery use outside this Kodi casting scenario.