Is your keyboard chattering? How to tell

Watch the same key light twice

Open the keyboard test and tap a key once. If the counter jumps by two, or the key flashes twice, the switch is bouncing. That is chatter, not a software repeat rate.

Try another key in the same row

If only one key does it, the switch is worn. If a whole row does it, the board or the cable is the more likely fault. The test forgets each press when you leave the page.