The keyboard itself (Ducky one 2 mini) allows the debounce rate to be adjusted on the keyboard itself. Link: https://cdn.discordapp.com/attachments/675025065380675594/757556252262924379/Screenshot_20200921-125745_Drive.jpg
Is it possible that perhaps, because of the fact that the keyboard has been in use for a very long time, the D key has begun malfunctioning slightly, and that is why it is the only key to show these weird patterns when on 5ms debounce?