i wanted to try to avoid the ghost entries which happen when you update the item with a new relation, as you see above. then the old entries always remain in the database, thus i thought i might update to cascade. but unfortunately it seems directus is then maybe trying to delete everything and is doing this in multiple transactions which sqlite does not support (this is only my guess)

if using the cascade on deselect is not recommended, then how can i avoid these ghost entries which happen upon setting new relationships when updating the item?

in regards to the clean up i am now using a action. but honestly this feels wrong

action("posts_tags.items.create", async ( {payload,key}, { accountability,schema,database }) => {
    //clean up
    const junctionServiceAdmin = new ItemsService("posts_tags",{ schema, knex: database });
    await junctionServiceAdmin.deleteByQuery({ filter: { _or:[{posts_id: {_null:true} },{tags_id: {_null:true} }]}});
  });

if using the cascade on deselect is not recommended

It is! How you're configuring it is the recommended approach. I'm assuming it's simply a case of the wrong transaction connection being used somewhere in this flow 👍🏻