Help identifying IC - top marking N14D4
Desqa's comment, combined with rdtsc was enough to figure it out. It is functioning as a level shift.
It IS reversible and it's a pair of NPN transistors. I figured it was a SOT6 package, googling n14 sot6 led me to here:
https://cdn.instructables.com/ORIG/FH3/DM1V/HRTWJLSB/FH3DM1VHRTWJLSB.pdf
From there, I found DDC114YU, which led me to
https://www.diodes.com/assets/Datasheets/ds30345.pdf
That's exactly what it is, the GPIO is triggering the left transistor for transmit mode, and the resistor at the top drives the right transistor when in receive mode.