Click the title of the post I linked above (or click here: Scan Issues - Marlin - Diode laser - #10 by m1rk00 )
It shows that he comments out the “if( ELAPSED” line, and the line above it. He leaves alone the “planner check” line, and comments out the one below it.
The current code only updates the PWM to the fans 10 times per second, which is not remotely fast enough for a laser.