After running CO2 for a while and running into the same issues I do agree with what @ExTek90 has to say: I think there is something about CO2 that pulls out non-cannbinoid plant compounds that have similar boiling points as cannabinoids. It might also pull natural plant acids (that are not extracted by ethanol or butane) which can interact with cannabinoids in the distillation process.
I can tell you from experience that adsorbents, doing your winterization carefully, and really really careful distillation don’t really help so much.
You might want to pursue neutralizing the pH of the ethanolic winterization miscella mix. Perhaps use something gentle like sodium bicarbonate or potassium carbonate + a 190proof ethanol mix to adjust pH to 7.0 before rotovap and then distillation. That was the one experiment I never checked off the list and it’s worth checking out. I experienced degradation issues post-distillation, and issues with no degradation but no improvement in potency. I always suspected they were two independent issues that were particular to CO2 (never experienced them with ethanol or butane crude). The strain of cannabis might also vary greatly with CO2 distillate, ie., different strains have different level of plant compounds (or grower contaminants) that CO2 will pick up differently.
Anyhow, if you want to talk more about it hit my DMs. Also, if you want to just upgrade to a high value ethanol extraction solution, I’ve got a great system for you.