Only the information obligation according to Art. 14 GDPR provides for an exemption in favour of professional secrecy:

Art. 14 V d: „Paragraphs 1 to 4 [information obligation] shall not apply where and insofar as where the personal data must remain confidential subject to an obligation of professional secrecy regulated by Union or Member State law, including a statutory obligation of secrecy.”

The expectation of confidentiality must be laid down in law or in a statutory obligation. Professional relationships of trust between private individuals are protected, as are official secrets.

It is unclear why only the aforementioned information obligation, but not other data subjects' rights, know such an exemption. In particular the right of access under Art. 15 GDPR could be considered as a provision that would require a corresponding exemption. Insofar as the fundamental rights of professional secrecy holders (such as the freedom to choose an occupation [Tile CO.16]) are at issue, direct recourse to the fundamental rights of the Charter of Fundamental Rights and the principle of proportionality (Art. 52 I CFR) may be considered. Cf. also Art. 1 II and EC 4 p. 2 GDPR.