Might sound obvious but you'll be surprised how much we resist just airing the issue: Have you tried talking to the person (Product Owner/direct manager) human-to-human? Tell him/her that you are aware how stressful it is for the PO with the impending release. Remind him/her how much better his/her products will be if developers are motivated and work as a team.

“If you would persuade, you must appeal to interest rather than intellect.” – Benjamin Franklin.