Hi @ponthijr
According to our testing, when you use &message=<precanned text>, the text will be displayed to multiple users, which should be a default behavior of Teams.
If you want to avoid this issue, we recommend that you only use https://teams.microsoft.com/l/chat/0/0?users=<user1> and enter the text manually in the chat box.
To fix the problem more quickly, you can send a feedback directly to Microsoft Feedback to add it in future updates.
Many features of our current products are designed and upgraded based on customers’ feedback. With requirements like this increase, the problem may well be released in the future.
Thanks for your understanding and support.
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