Will Zeeën drain my battery?
No more than you'd expect from an app that uses Bluetooth and location.
Zeeën is built to keep this lightweight. The proximity signals that power your Nearby and Around feeds are low-power by design, Zeeën isn't constantly scanning at full intensity in the background.
Battery impact varies a bit by phone and by your own settings, but for most people it's minimal, similar to having Bluetooth on for headphones or a smartwatch.
Related:
Why do I need permissions?
Does the app need to stay open?
Why am I not seeing anyone near me?