According to the Amrvis documentation (step 2 here), after cloning the amrvis repository one should point the palette variable in ~/.amrvis.defaults to the appropriate file within your local amrvis repo. How is this resolved when Amrvis is installed via spack?
I was able to install amrvis, for example with
spack install amrvis dims=2
However, attempting to visualize a plot file results in a warning
Can't open colormap file: Palette