A wildcard index cannot be unique
What changes in A wildcard index cannot be unique compared with MongoDB and what your application has to do.
This difference is of the Stronger guarantee kind.
What MongoDB does
collMod accepts turning a wildcard index unique, writes an invalid index and the server stops.
What TeselaDB does
It answers error 67, which says wildcard indexes do not support unique.
What your application has to do
Use a unique index on specific fields.