Is search broken? I haven't been able to search anything for over a month.
It does seem to be. TBH the on-site search has never been great, I'd recommend using "site:geekhack.org" on google or another search engine instead.
That said, I did raise this to the dev team to see about addressing.
Geekhack search still works if you turn on the "Search in topic subjects only" option. I also highly recommend searching one board at a time.