I did the same, and I also cancelled my premium account (I know, I shouldn’t have paid for it in the first place).

There is a sub called r/lounge which is a “reward” for paying for Reddit Premium, and you also get temporary access if your post gets gilded. It’s a pretty inane sub mainly for just idle chatting, but I really noticed the amount of posts in there drop off a cliff in the final week. They hide the subscriber count, so you can’t see how many members there are. But just judging by post activity, I guarantee that it at least cut in half.