Sorry for the rejection.
I am no expert as I myself have applied for GTV in the last week and awaiting for the response. But still trying to answer your question as I have chosen the same criteria.
Based on feedback it seems that they weren’t able to understand the contributions made by you in those projects and the impact that was created by your contribution to those projects.
My first question is the projects that you were part of, was it a product for your clients? If yes mention your exact contribution that you made to that product and not as the whole team.
Secondly you can use architecture design of your contribution as evidence and show what impact was created by your contribution in the projects. To support this evidence also you can use a reference letter from someone who can talk about the impact created by your work.
It would be good if you can mention what evidence
You have given. I myself will get some more idea about the same and will get to know about my application too.