Thank you for the feedback. Changing the default setting is under review by the feature team, and your feedback is very useful as they are evaluating.
An error occurred while saving the commentAndrew Figueroa commented
This is a duplicate of this idea: https://microsoftteams.uservoice.com/forums/555103-public/suggestions/30990691-disable-send-message-on-pushing-enter-shift-ente
(I agree with this idea, but just forwarding others and increasing the likelihood that they will be combined, increasing the vote count)