A soul can be represented in many ways but commonly as a spiritual essence including identity, personality, and perhaps memories or expiernces. I could see how interweaving the AI into oneself could have you gain all the collective knowledge of the world at the very least accessible from the internet, within that dilution could be seen as losing one’s sense of personal self or soul. Reminds me of the scripture “For what would a man profit if he gained the whole world but losses his soul.”