Official patch notes from Capcom and community trackers like Resident Evil Fandom highlight that version 1.03 was primarily a compatibility and stability patch:

Capcom, the developer of Resident Evil 7 Biohazard, typically responds to piracy by releasing updates that not only improve the game but also include anti-piracy measures. The cat-and-mouse game between crackers and game developers continues, with each side trying to outsmart the other.

Key changes included (practical impact)