Because he said they edited Kamala Harris' interview?
Guess whose interview on 60 Minutes was heavily edited as they repeatedly removed claims he made that were demonstrably false? They released the full interview on video and 60 Minutes over and over edited out claims Trump made that weren't true and made him look bad. Such as claims about what Biden gave to Russia, and things he did that was tough on Russia.
Over and over they cut stuff out that made him look bad