GTA Trilogy Definitive Edition Gets Surprise Update on Console and PC, Adds Visual Features That Were Exclusive to Mobile Versions

It's literally in the article what was updated

In contrast, the mobile versions of Grand Theft Auto: The Trilogy - The Definitive Edition, released in December last year, met with critical acclaim. Players praised the ports for fixing several issues found on the console and PC versions, including lighting, shadows, reflections, and draw distance. A Rockstar Games blog post published at the time mentioned that these ports include a new classic lighting mode "that restores the look and feel of the sky in the original games."

Now, finally, this classic lighting option is in Grand Theft Auto: The Trilogy - The Definitive Edition on PC and console. Early reports indicate sweeping visual improvements across the board that are already going down well with fans.