Pressing down arrow key to scroll in search results will unexpectedly scroll

[Susko3]

To repro:

1. Open cs.github.com
2. Search for something
3. Press ↓ (down arrow) to scroll
4. The page will unexpectedly scroll (without the usual animation), almost to the bottom

Browser: Firefox 95.0.2

unknown_2022.01.12-00.36.mp4