Additional chat-related features and issues within Microsoft Teams for business
Dear @Edwin Van De Brand - (C),
Regarding the issue where you cannot use Paste function in Microsoft Teams, Microsoft has officially acknowledged this as an ongoing incident. The product team is actively working on a resolution.
Here is the detail about the incident and the next update will be released on April 28:
In the meantime, you can use Ctrl + V (Windows) or Cmd + V (MAC) to paste your data or using Teams web as a workaround for this incident.
Please feel free to let me know if you have any further concern.