Hello Rototti**,**
Good day! Thank you for reaching out to Microsoft Community.
I understand that you are experiencing an issue with the message parameter not working when creating a chat using a deep link. I apologize for any inconvenience this may have caused you.
Regarding your concern, I would like to inform you that the message parameter is not currently supported in Microsoft New Teams.
It's not a bug. The documentation you referred to is not outdated but the feature has problem working with New Teams, as a result the Microsoft development team is still working on it.
Here is the Microsoft Road Map link for deep link improvements: Microsoft 365 Roadmap | Microsoft 365
For the moment only work around it to work with previous version of teams.
And we apologize for any confusion this may have caused.
I hope this helps! If you have any further questions or concerns, please don't hesitate to ask.
If none of these step's work, please let me know and we can explore other options.
Thank you for choosing the MS community.
Looking forward to your response and having a great day ahead!
Sincerely
S M Nazmun Nur | Microsoft Community Moderator