DIAGNOSIS If it's hardwired, the battery shouldn't be draining at all—it should be kept at or near 100%. The fact that it's draining means the internal battery is powering the device because it's not getting sufficient *continuous* power from the wires.
FIX This points directly to an underpowered transformer. Most old doorbell transformers are 10VA (16V) or lower. The Doorbell 4 needs a transformer rated at least 30VA (like 16V-24V, 30VA). Check your transformer (usually in a chime box or basement) and upgrade it. This is a hardware fix, but it's the real solution.
IF THAT DIDN'T WORK If you have a new, powerful transformer, the issue could be a setting. In the Ring app, go to the device settings > Power Mode. Ensure it's set to "Wired" and not "Battery." If set to Battery, it will ignore the wires and run off the battery until dead.
HEADS UP Even with a proper transformer, if you have a long run of thin-gauge doorbell wire, you can get significant voltage drop. If the transformer is far away, you might need to re-run with thicker (18-gauge or lower) wire.