Cant update user value in Firestore

Hi, i want to update firestore field via node.

Try 1
as a new value i pass data.user_id, but in console i see in the Input section: "_ref:[object Object]"

Try 2
i stringify it just to make sure, that i have access to this data, i see it, and when i pass to firestore stringyfy node output - i got an error.

Try 3 (no screenshot)
If i hardcode user ref - document is updated correctly so it is not firestore rules related.

Any ideas?

Oh, i tinkered in node code, so maybe i messed up something...