For the speedrunning community, 1.0.3.1 is a historical artifact. It was the first version where the infamous "Storage" glitch—allowing players to carry items or abilities between save files—was significantly nerfed, though not entirely removed. This changed route planning overnight. Many veteran runners consider 1.0.3.1 the last version that still captured the "wild west" feel of early Hallownest, before later patches tightened every loose screw.
If you want to look closer at early builds of Hollow Knight, tell me: Hollow Knight 1.0.3.1