Hello Fabien Leveque,
Welcome to Microsoft Q&A.
surface hub is an enterprise-level collaboration device launched by Microsoft. This device belongs to Surface for business. So I think you might need to ask Surface Support for Business about this issue:
Contact Surface Support for Business and Education customers - Surface | Microsoft Learn
There is indeed a trade-in policy for individual users, which might be similar to the "recycling program" you mentioned here. But I'm afraid this doesn't apply to Surface Hub.
Microsoft – AI, Cloud, Productivity, Computing, Gaming & Apps
Best Regards,
Kai Ho | Microsoft Q&A Support Specialist