So I've been using Clickteam Fusion for most of my life, and it's where I'm the most comfortable and work the easiest. I know I should get off of it and find something better (especially with the way they've been getting lately) but again, it's where I'm most comfortable.
Fusion comes with a built in palette swapping function but it's the slowest thing on earth. Like, slow enough that I don't know why they even included it. Changing just a handful of colors can take 2-4 entire frames, and that's for doing it once. Cycling a palette is straight up out of the question, unless you enjoy bringing a Ryzen to its knees.
If I could do this on a shader, it would be tremendously faster. For example, Fusion also has built in sprite rotations that also aren't very fast (or nice looking) but it's not hard to find a rotation shader that does the job with a tenth of the compute lag.
The only issue is that I don't know how interoperable GM shaders are with Clickteam Fusion and I know absolutely zero about shader language so I wouldn't know how to convert things if there were differences. (The latter is a big point of frustration for me, because there are a lot of great shaders out there for CRT effects and the like that I wish I could just drop in to Fusion and cannot)