I thought it might be Generations, but that was 257.4 MHz https://www.youtube.com/watch?v=6A9IZHWz45Q&t=20s
After that, I'm sure the Owner's Manual that comes with your new Enterprise-class Starship now has a "DO NOT DISPLAY YOUR SHIELD FREQUENCY" in the "Warnings" section
Also, given Starfleet's continued examples of not learning their lessons from previous encounters, I suspect all ships still display the shield frequency in big, bold font. Possibly even visible from the viewscreen of the bridge on one of the rear consoles.