Hello,
That's my first try of working with solutions.
For that, I've created a new solution and add an existing canvas app in that solution.
In this canvas app, I have a triggered flow that needs 3 parameters. But I have this error:

My flows cannot work with 2 parameters and it still works perfectly in the classic environment without solution.
I cannot recreate the flow from scratch because, in the dynamic content, I cannot add a parameter from Power Apps, I can access only to the environment variables.
I think the problem is only linked to the fact that I work with solutions. But that's the goal of my exercise so I should find a solution for this flow.