In the new canon Mon Mothma's defining act as the first chancellor of the New Republic is to disarm the Galactic Military in the face of an obviously bellicose imperial remnant (who totally promises they aren't interested in reconquering the galaxy), and then she promptly retires. This leads to individual systems militarizing themselves and then pledging support to the First Order, who easily destroy the New Republic at the first opportunity.
It almost seems like political satire, but no, it is just a hasty post hoc rationalization for returning to the A New Hope status quo.
so basically the series is going to tilt into how the partisans are extremists that need to be dealt with so the moderate faction with Mothma is the right answer because the alliance is based on hope and having the moral high ground
Yeah taking into account R1 and the OT it seems like Mothma gets dragged along through the revolution by the more radical wing of her faction, pretty sure she isn't relevant at all in the grand scheme until after the Empire is defeated and she becomes a politician in the New Republic (and fails to stop the First Order from rising lmao).