PMP Practice: Identify and Analyze Conflict Sources

Faisal Al-Dosari is the Scrum Master for Tahini Supernova Studios, a team developing a mobile meditation app. During the last three sprints, the UX designer and the lead developer have been in persistent conflict over feature implementations. The designer insists on elaborate animations and interactions that the developer says are technically unfeasible within sprint timeboxes. Both escalated the issue to Lila separately, each blaming the other for slowing down progress. The team's velocity has dropped 35% over this period, and two planned releases have been delayed. Lila facilitated a team retrospective where both parties agreed to collaborate more closely, but after two weeks the conflict has resurfaced with the same arguments. The designer just sent Faisal an email saying she's 'done trying to work with someone who doesn't value user experience,' and the developer responded in the team Slack channel that 'design keeps ignoring technical reality.' What should Faisal do to recover the team's effectiveness?