I’ve used NIC cube grids to block off the whole area under my bed, and then put a bed skirt over the top so it looked nicer. It worked great!
But as long as there’s nothing under there that can harm her there’s not really a problem with it! If you decide to give her access, watch to be sure she’s not trying to crawl into the box spring. Not sure what kind of bed you have, but a past bun of mine ripped the fabric on the box spring and would crawl up inside it, which was not great! I’ve also heard of buns chewing carpet or deciding to make a new litter box area under the bed. Some people compromise by blocking off most of the bed, but keeping a small area available near the edge as a hide for them.
Agree that giving her other tunnels and hides will help too. My buns love their maze haven.
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The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.