Nintendo ceased first-party Game Boy Advance game production in 2005. The final first-party release was WarioWare: Twisted! (JP: Oct 2004, NA: May 2005, EU: June 2005). A handful of third-party titles trickled out until ~2007 (e.g., Final Fantasy VI Advance EU 2007), but Nintendo itself stopped manufacturing cartridges and publishing new GBA software after 2005.
Active communities still release new games on physical cartridges via:
These are unofficial, but they keep the platform alive.