In the newest mac client you removed the ability to do option+<return> to submit a carriage return and switched it with shift+<return>.

This is probably the most annoying thing you could have possibly done....

whenever someone has the need to input carriage returns in their message it's because they're probably dealing with something large and/or trying to format something complicated. Changing this feature has resulted in everyone in our company accidentally sending unformatted/incomplete/wrong text constantly since it's muscle memory at this point for everyone.