Here is a story that clearly indicates the problems where confidential informants are then used as witnesses.
There is an all to common opinion that someone who is a confidential informant is also suitable to be then used as a witness. Essentially this is about lazy law enforcement.
There is a clue in the name ‘confidential informant’ Confidential means we don’t expose them.
A witness is someone we intend to testify.
Conflating the two brings huge problems including dubious convictions and the exposure of informants to risk to their life.
Agencies need systems and processes to manage any conflict between the two.