It’s pretty much one of the only ways to create the effect you’re looking for, you probably wouldn’t notice the neon parts since they’re usually scaled to a relatively small size and placed directly in front of the camera.
I tried using a viewportframe and a neon part, didn’t work for me, maybe it will for you. However I found that using glass material and messing with the reflectiveness & transparency can give off a nice glass overlay effect.
I know I’m late, but maybe you could add the Blur to the Camera (local of course), and adjust it when needed.
Pros: Gives you a dynamic-blur.
Cons: Blur is on the whole screen, and is not a GUI.
(Won’t blur GUIs, but you can add transparency to the GUI to make it look somewhat blurry too.
However, if you’re just looking for a blurry background, then I’d definitely go for the “BlurEffect”)
I think you can blur it by making a separate blurred image in Photoshop that has a transparent background (By that I mean no background at all, no colors etc…) and then just make an image label and just scale it the size you want.
For more info please reply to this reply!
Edit: Sorry for the late reply!