I’ve been wondering if something sitting on top of the beans in the hopper (eg a bag of rice) would stop new oxygen reaching the beans as their level drops. Ideally, the hopper would be cylindrical and the object a simple disk, but mine is the usual conical shape. Or am I over-thinking this?
Only grind what you need. Nothing will help once in the hopper.
And on the first use of the day, do a one-second grind and discard, to remove the stale grinds from previous day.
Or leave them in for an earthy staleness 🙃
EDIT: Disregard the above, clean your burrs regularly to remove staleness.