B402/404X NRF52840 IO Frequency

Our PCB designer has pointed out to us that many of the digital IO pins, most importantly the SPI pins, are only rated for 10 KHz only according to the nordic datasheet. This seems strange to me, as we use SPI at 30 MHz, so I am wondering if there's some magic going on in the background or if we are misreading the nordic datasheet?

From the B402 datasheet, SPI is pins P1.-3, P1.13-15.

Pins with the same P1.* naming are listed starting on page 577 here: https://infocenter.nordicsemi.com/pdf/nRF52840_PS_v1.7.pdf

There's a pin multiplexer in front of most pins on the nRF52. The GPIO block is different than the SPI block, which is why the GPIO can be relatively slow but when configured as SPI, it's fast.

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