Wet or dry trimmed? What kind of trimmer?
How long since the material was harvested? How was it prepared and stored? It darkens with age.
What color are the trichomes? Clear, cloudy, or amber? Amber will always extract darker.
Wet trimmed material has more bruised cells than dry trimmed, and a spinning blade trimmer lubricated with vegetable oil to keep it from getting coated with resin, is both bruised and contaminated.
Bruised cells spill their contents, making them available to the solvent, that otherwise would just be dissolving resin glands on the surface of the plant material.
Oil contamination is not readily removed, leaving a goopy extract, which is darker if you continued to try and purge the vegetable oil.
We are extracting molecules between about ten carbons in the chain, to about 30. The C-10 through C-22 molecules in the raw oleoresin extracted, have little color, but once you reach C-30 sized molecules, you have chlorophyll, plant waxes, and anthro cyanin color pigments.
The anthro cyanin color pigments, are also glucosides (plant sugars) which caramelize and darken with heat.
Decarboxylation darkens THCa, and I've noted that heat also darkens Clear extracts, which ostensibly is the C-21 cannabinoid fraction, leaving me to wonder if CBN is also darker.
If the material is too dry, there isn't enough moisture to freeze the water soluble chlorophyl binding proteins in place, so freezing doesn't help much.
If you freeze the material and then use a solvent that isn't at subzero temperatures, it just melts it again and has limited effect.
If you use a polar solvent (dielectric index above 15), chlorophyll contamination will be a problem, because of the magnesium atom in its tail making it polar on one end.
The presence of water in non frozen state, can also transport chlorophyll as micelles, even in a non polar solvent.
Sooo, what can you do, given that you can't make chicken salad out of chicken manure?
You can take your best shot on a sample and see what you get. Based on those results you can move on or to Plan B.
A non polar extraction like propane, butane, or pentane would pick up the least amount of non targeted elements.
An extraction done on 0F frozen material, using -40C propane/butane mix, would be what I would personally try first.
You can soxhlet with pentane, and winterize with ethanol to remove the plant waxes, or with hexane or heptane for that matter, but our livers can turn residuals of those two into carcinogenic 2.5 Diones, so I prefer pentane.
You can also clean it up afterwards, but at the cost of the monoterpenes, reducing aroma and flavor.
https://skunkpharmresearch.com/getting-the-green-and-waxes-out-afterwards/
Expect significant losses with carbon filtering, of targeted cannabinoids, along with the non targeted targeted molecules you seek to remove.