There are three main analog blocks inside the MAX22190 contributing to the minimum pulse width spec, front-end comparator, sampling stage and digital filter.
The comparator stage at the front end has a typical 2us delay. The sampling stage has a typical 1us delay due to 1MHz sampling rate in bypass mode. In the bypass mode, the digital filter is bypassed thus the delay is 0. When digital filter is enabled, the filter delay should be taken into consideration determined by the programmed filter value in the FLT_ registers.
So in bypass mode, the minimum pulse width is 2us +1us = 3us.