Here is a helpful excerpt I use from another rabbit community to address thumping concerns:

“My rabbit is thumping! What does it mean? A rabbit thumps when they are feeling afraid, alert, or threatened. A single thump can indicate displeasure. Rabbits will often seek safe refuge while thumping. Remember that rabbits have better hearing and smell than humans and their field of vision functions differently, so often times rabbits may be perceiving something you can’t.

What do I do? If you can identify and remove the cause of the thumping, you can try doing so. You can also attempt to distract your rabbit with food, pets, music, or toys. In most cases, a rabbit will naturally stop thumping once the stimulus has passed or by becoming habituated to it. If your rabbit is thumping while outdoors, they may be perceiving a predator. Please bring your rabbit indoors if you suspect they are in danger.”

Mine has been doing this ever since the Amontillado incident.

Maybe there’s a mouse or something in your wall? But also bunnies just thump at things sometimes. Often they hear things we can’t that are off in the distance (or a smell wafts in on the wind).

That wall knows what it did.  It knows.