"Dealt about" is not a standard phrase. "Dealt" is the past tense of the verb "deal," which can mean to distribute, to handle, or to buy and sell. The phrase is likely a misunderstanding of "dealt with," which means handled or addressed, as in "the issue was dealt with". "Dealt about" could also be a typo for the 2017 documentary film Dealt, which is about the life of blind card magician Richard Turner.