By its explicit terms, the Code governs only the judges of the lower federal courts. It does not apply to Supreme Court Justices, nor has the Supreme Court formally promulgated its own ethical code. As a result, there is presently no single body of ethical canons with which the nation's highest court must comply when discharging its judicial duties.
But it is true. Justices aren't normal judges. Yes - they all started off taking the same oaths. Once they were appointed as justices things changed.
https://www.congress.gov/crs_external_products/LSB/HTML/LSB10255.html
https://www.judges.org/news-and-info/almost-all-judges-believe-supreme-court-justices-should-be-subject-to-an-ethics-code/