I have this need too! I made a request here, I think it’s the same: "Contains" formula function
BTW, you can check the Public ID, it’s more robust than name. I usually make a formula on the entity “Public ID Code”: “{” + [Public ID] + “}”
Then join based on this formula on the entity that has the collection, then run the “contains” check (I usually use Find() instead of regex, but I think either works.)