On Steam or Epic Games, right-click the game in your library, go to Properties (or the three dots), and select Verify Integrity of Game Files to repair corrupted installation data.
GTA 3 (especially the Definitive Edition ) often struggles with "special characters" in the Windows user profile path. gta 3 save unsuccessful fix hot
Saving the game in GTA III - Rockstar Games Customer Support On Steam or Epic Games, right-click the game