.

[icpcb]

.

[tooki]

Probably to prevent ghosting with those specific keys.

[wizard69]

Now that you wrote it: I remember the tutorials all having diodes next to the switches to avoid ghosting but this pad doesn't have these. Thank you, didn't think about that!

I have no idea what ghosting is but if they are using more keys than required there is something special being done with one or more keys.   Maybe one needs to generate an interrupt.   Even there, 14 is an odd increase in line usage.

[tooki]

Now that you wrote it: I remember the tutorials all having diodes next to the switches to avoid ghosting but this pad doesn't have these. Thank you, didn't think about that!

I have no idea what ghosting is

https://deskthority.net/wiki/Rollover,_blocking_and_ghosting