That's quite possible if you have a fast carrier. Currently ZapStream is encoding server side for the output resolutions (source, 720,480, 360) based on the viewers bandwidth and there is no option to chose the resolution on the player yet.

Now, I'm encoding with 12k/s on AMD to have crisp video on fast paced games with a lot of frame changes. On Nvidia you could push with 6k/s to get a similar result. If you're watching my stream in source resolution with a fast carrier then you'd be using a lot more bandwidth opposed to watching at 480p which is more than sufficient on a small display like a phone.

Basically you're watching my output for desktop, tablet, flatscreen in full resolution thus your consumption. If you're watching a creator who's streaming at 4k-8k you'd use about half the data but, at this moment, you would also watch their stream in 1080p or 720p or whatever their output is because of the reasons above.

This should however not affect your phones cache that much. That data is probably nostr events and other data caches to your nostr clients and from other apps.

I think we'll see output resolution as an option on the viewers side soon. Which will help you reducing the data you're using when watching streamers by setting one more suited for your display.