I have bought headphones WH-1000XM5 an it it picks up all the background noise during Microsoft Teams New calls, so the people in the meeting can hear my colleagues. I am disappointed and considering to return them, as this is my main use for them.

User David A Land has narrowed the problem to only Teams New (not Teams classic). Other headphones work fine in Teams New.

You can find that dozens of people are reporting to experience the same issue through Reddit and Microsoft communities:

https://answers.microsoft.com/en-us/msteams/forum/all/sony-wh-1000xm5-issue-with-ms-teams/a9f49b82-1...

https://www.reddit.com/r/SonyHeadphones/comments/x7l0hh/wh1000xm5_mic_picking_up_too_much_background...