Just found the solution in case anyone else is looking. I simply pressed down on the boot lid from the outside as it closed. It didn’t make the noise. Opened and closed it as normal a few times after and it’s fine now. Must’ve been something blocking it - dirt, rubbers lifted a little, not sure. But the noise has stopped.
Did you figure this out please? Mine has started doing it recently. Boot closes and pulls in close as normal and then I get a sound like a servo triggering repeatedly, or a gear skipping, maybe?