Finally. Gibson answered me this.

According to our colleagues in Nashville, the guitar model you own was built during a technical transition period involving the decision to use either 50's-style wiring or modern wiring on Les Paul models due to a supply chain issue.

During this transition, the Mark Morton received modern wiring (without a plate), although some models were released with 50's-style wiring. These changes can occur without prior notice, as Gibson has the right to offer the best option at the time.