I don’t have Final Cut Pro, and I don’t have the Film Grain effect. Could applying a super light filter of video noise be a good secondary option to fix the look of the 2011 Blu-ray?
What editor do you have?
The two options are apply noise but heavily adjust the settings to make it mimic film grain ( https://www.youtube.com/watch?v=k7P_sSUH9fE ) or you simply download a 35mm film grain “template” and drag it on top of your movie then set it to “overlay” mode (or do the mode Hal did) and adjust the opacity as necessary. So the second method can be done on really any editor as long as you can find some grain templates (here are ones I tried https://drive.google.com/drive/folders/1oe-i47Yvb-Q3x0gX4kpPMySkCQmgGCHP?usp=sharing )
This might be real embarrassing, but I use Movavi Video Suite.