If you are trying to exclude certain ids from showing up, then
Recommendations has a param that is built for that: function
targetPageParams() { return { "excludedIds": ["352", "223", "23432",
"432", "553"] } }
https://experienceleague.adobe.com/docs/target/using/recommendations/plan-implement.html?lang=en
For your particular question, I don't think you need to stringify the
param value since Adobe will be expecting a list (array) on both the
left (param) and right (item catalog column) side. I ...