Can't update any attribute on the collection

I have collection named deals, with a lot of attributes and I wanted to reduce some of them in terms of size (string type). However I am encountering such errors each time in the dashboard:

This is exact error from the api:

{ "message": "Invalid index attribute \"users\" not found", "code": 400, "type": "column_index_invalid", "version": "1.8.0" }

We don't have such attribute in this collection, we are updating deals collection, payload is:

{"required":true,"default":null,"size":4000}

I have a few indexes on the collection, already tried removing all of them and updating the attributes, but the error remains. There was not any index on this collection named "users", so its hard to determine what is causing the issue.