Ethical Responsibilities of Reviewers

Confidentiality
Material under review should not be shared or discussed with anyone outside the review process unless necessary and approved by the editor.

Constructive critique
Reviewer comments should acknowledge the positive aspects of the material under review, identify negative aspects constructively, and indicate the improvements needed.
Reviewers have the responsibility to identify strengths and provide constructive comments to help the author resolve weaknesses in the work.

Competence
Reviewers who realize that their expertise on the subject of the manuscript is limited have a responsibility to make their degree of competence clear to the editor. Reviewers need not be expert in every aspect of a manuscript’s content, but they should accept an assignment only if they have adequate expertise to provide an authoritative assessment. A reviewer without the requisite expertise is at risk of recommending acceptance of a submission with substantial deficiencies or rejection of a meritorious paper. In such cases, the reviewer should decline the review.

Impartiality and integrity
Reviewer comments and conclusions should be based on an objective and impartial consideration of the facts, exclusive of personal or professional bias. All comments by reviewers should be based solely on the paper’s scientific merit, originality, and quality of writing as well as on the relevance to the journal’s scope and mission.  Potential reviewers who are concerned that they have a substantial conflict of interest should decline the request to review and/or discuss their concerns with the editor.

Disclosure of conflict of interest
If reviewers have any interest that might interfere with an objective review, they should either decline the role of reviewer or disclose their conflict of interest to the editor and ask how best to address it.

Timeliness and responsiveness
Reviewers are responsible for acting promptly, adhering to the instructions for completing a review, and submitting it in a timely manner. Failure to do so undermines the review process. Every effort should be made to complete the review within the time requested. If it is not possible to meet the deadline for the review, then the reviewer should promptly decline to perform the review or should inquire whether some accommodation can be made with respect to the deadline.

Reference; https://www.councilscienceeditors.org/resource-library/editorial-policies/white-paper-on-publication-ethics/2-3-reviewer-roles-and-responsibilities/