I believe the reason for the change is that "painting the environment" was not considered the purpose of the device.
This is what Google AI told me:
In Battlefield 6, the portable laser designator is a Recon class gadget that marks enemy vehicles and targets for guided munitions, allowing teammates to quickly lock on and destroy them. It operates from a ground tripod and allows players to remotely view and control the designator from a safe distance, even providing a 360° view.
Purpose
Target Designation: Its primary purpose is to "paint" enemy vehicles, such as tanks, with a laser signal that is invisible to most enemies.
So, my thinking is that painting the environment such as buildings, walls or groups of soldiers, for example, was not the intent of the device.