Combining regression therapy with psilocybin truffles carries a key risk: heightened suggestibility. In that state, leading or loaded questions can seed confabulation, making it easier for false memories to form.
The experience can also be emotionally overwhelming. Intense imagery and symbolism may be misread as literal memory, and strong feelings can blur the line between insight and invention.
If you choose to combine them, safeguards matter: work only with an experienced, non-directive facilitator, agree on neutral questioning, set clear stop signals, and plan careful integration afterward. Recording prompts and questions can help check for suggestive wording later.
For a concise overview of risks and good practice, see this discussion. Stay safe and keep a critical eye on any memory claims that arise.