Hunter talent · row 4 of Marksmanship, from level 25 (20 with Talented 5/5) · Physical

Mortal Shots

Increases the critical strike damage bonus on all ranged abilities by 6/12/18/24/30%.

Game files · build 1.60.1.70245Read from the WoW Forever beta client, build 1.60.1.70245.

Compared with Classic

Classic tooltip

Increases your ranged weapon critical strike damage bonus by 6%.

Data	Classic	Forever
effect 2	present	removed
effect 1 value	6	30

What Blizzard said about Mortal Shots, each line checked against the files.

Matches the files
Mortal Shots: Now has pre-requisite of Careful Aim.
The files Mortal Shots (19485) requires Careful Aim in the 70245 tree; in Classic Era it required Lethal Shots (talent prerequisite).
Mortal Shots Careful Aim Class deep dives: Hunter and Druid

69876 Sep 16First beta build we archived. No changes in the client files since.