YGO Judge doesn't show a consent banner yet: no non-essential storage (audience measurement, etc.) is used on this site for now.
A session cookie is used if you log in, to keep you signed in between visits. Everything else (language, preferences) goes through your browser's local storage — always as part of normal site use, never for advertising tracking.
YGOProxy (the proxy generator in the family) already has an active consent banner, with minimal anonymized audience measurement. YGO Judge will follow the same categories and consent principle the day audience measurement is added here.