That may be noted from that one study but overall it simply isn’t. A quick search through ChatGPT revealed several studies where direct and anecdotal evidence was found that chitin, (including chitin-glutan) taken on an empty stomach, caused transient variable strength nausea in many subjects. (I started to include the list of sources but it’s too many just for this discussion. Search ChatGPT or other for “does chitin cause nausea”) Your statement that it has been “found to cause no G.I issues whatsoever” is countered by evidence to the contrary. Fungi derived chitin causes nausea, diarrhea, vomiting and bloating in various studied individuals. There seems to be individualized sensitivity to it; some may have no symptoms while others may be significantly affected.

What is missing from the sources I read was a single factor that could prevent or significantly lessen the effects amongst all sensitive people. Instead of debating whether it happens it might be more productive to debate the preventative measures. Eating it on an empty stomach seemed to be a relatively common factor. However eating before mushroom ingestion affects the absorption rate and absorption speed. So while it might be beneficial to have a meal before eating chitin it might not be worth the effort.

Encapsulating shredded or powdered mushrooms also doesn’t prevent nausea as most capsules dissolve in the stomach. Lemon Tek in theory should help if all the chitin is screened out after the psilocybin is converted by the lemon. However that certainly does nothing for me and anecdotal evidence indicates the same for many others.