I have transcoding enabled in navidrome and tempus..it was all good for the past year, but today I got this warning that I consumed all my data plan. I listened to one hour of my music and just like that, bam, 17GB gone.
Not my lucky day I guess.
I use Tempus with Navidrome. Transcoding should be transcoding down to a format more appropriate for your bandwidth, so flac should be getting to your device as an mp4 or vorbis stream.
17GB seems high unless something else is going on, like your Tempus client trying to download all your tracks to your device.