Right of the supervisory authority right in context pf the submitted complaint
By derogation from paragraph 1, each supervisory authority shall be competent to handle a complaint lodged with it or a possible infringement of this Regulation, if the subject matter relates only to an establishment in its Member State or substantially affects data subjects only in its Member State.
Chapter VI, Section 2, Article 56, Paragraph 2
Regulation's subject matter
Competence of the lead supervisory authority (Article 56, Section 2, Chapter VI)