My favourite thing in the whole Fediverse is when I get a notification that someone has edited a toot I favourited or boosted months ago. Like, something in that toot has been bugging them for half a year. A comma that could've been a semi-colon. A spelling mistake they belatedly spotted. Some good information they wish they'd put in the Alt Text. And thanks to the magic of Mastodon, they can just fix it now, all these months later. I feel happy for them, knowing they can sleep soundly again.