The individual filters have generally been incorporated into (very) compressed .gmz files.
The old clut_xxxxx.cimgz files might still work. Use the Apply External CLUT filter (1) but also find the equivalent in Color Presets -> LUTs Pack -> Drop down menu (2) There are now hundreds of these presets. To help make a choice, render a collage of thumbnails (3)
Attachment:
preset.jpg [ 186.98 KiB | Viewed 3167 times ]
gimp_gmic_qt keeps a user profile, a gmic folder, same place as the Gimp user profile folder. Contains update files and saved "faves"...
The presets files are different. In linux they are in ~/.cache/gmic/ which on my machine contains two files gmic_cluts.gmz size 3 MB and gmic_lightleaks.gmz 247 kB As far as I know gmic downloads these as required.