Remote jobs that accept candidates from anywhere match every country filter, so a board focused on Australia and New Zealand used to fill up with them. Open Backfill → AI filtering settings and turn on Exclude worldwide remote jobs to leave them out.
The switch covers every rule and company source on your board. Remote jobs limited to specific countries or regions still come through, and worldwide remote jobs already backfilled onto your board are removed when you turn it on. See Leave out worldwide remote jobs.