Umm… what?

Last three days the elephant bush plant on the left had been losing leaves, it looked like it was under watered so I watered slightly (maybe a table spoon amount of water with a seaweed stress extract) and now all the leaves are gone but its neighbor is fine. Any thoughts? I’m not too worried about it, I’m going to loosen the soil with a stick and see if that helps it breathe but I’ve never seen this before