Can't insert a data in my collection from UI

Ok you have the message in the UI as a response of the call, right?

It means the error occurs in your admin backend (422 is unprocessable entity).
You should see a bit more info about it. Are you working in your development environment? If yes you should see the SQL queries that are tried to be executed at the moment.

Can we organize a call to fix the problem ? I can’t see anything except this in my admin backend, yes I’m working locally

Do you have this variable set on your .env file?

NODE_ENV=development

With this, you should be able to see the queries that are launched on your DB…