Hello Isabelle Cardoso,
Thanks for the question and using MS Q&A platform. Have you read this article: https://stackoverflow.com/collectives/azure/articles/75215092/how-to-parametrize-query-in-lookup-activity
I think you can try out a similar expression.
Himanshu
Please accept as "Yes" if the answer provided is useful , so that you can help others in the community looking for remediation for similar issues.