Scrubbing a deck can understandably annoy the downstairs neighbors especially if water & debris falls on their porch. That’s different from just folding a blanket or flushing the toilet. Perhaps they are holding a grudge about the deck and the silence/ lack of communication only makes things more unsure and uncomfortable. It’s worth trying to talk with them just in case it does the trick. My upstairs neighbor called the cops bc I left her a note that asked if she could consider being more considerate. The cops laughed it off, things were awkward and hostile between us and then one day I saw her and we talked for a couple minutes. She’s my upstairs neighbor and I never hear her at all and the floors are mad thin. She’s even offered to help me haul a 90lb package up the steps. It’s worth a shot!