The first question is who creates industry norms? Unless they are set standards like accessibility, or based on scientific psychological rules that defines the constrains of interface design, designers are the ones defining industry norms. They also define trends which may look like norms. Breaking those norms should always carry clear intention and should be validated with testing. In UX there are other forces like aesthetics, delightfulness or gamification where changes may happen more and norms are loose.

Address the dilemma by fostering collaboration. Begin with open dialogue to understand the designer's rationale and how their changes aim to improve user experience. Compare these ideas with industry norms and user expectations, leveraging usability data and feedback to evaluate the impact. Present objective insights to highlight risks or benefits of deviating from norms. If necessary, propose a compromise—conduct A/B testing to validate the changes against standard practices. Prioritize solutions that balance creativity with usability while keeping user needs at the forefront.