Not everyone is handy or knows how to use tools. Instead of a passive aggressive post on Lemmy. Perhaps talk to your neighbor comment on the fence posts and offer to fix it or show him/her how to fix it.

“Hey how is it going neighbor,I saw you fixed the fence. Love the new wood, did the hardware store not have the right length? Yeah that is a bummer, I have a saw, I’m sure I could help you get those planks evened out in a few minutes if you’d like.”

If they are a dick after that then post away.