Lots of loyalists have replaced people there. It's for sure incompetence.
Indeed, incompetence is basically guaranteed if the organization selects for allegiance rather than competence. But I prefer to think that at least part of this was malicious compliance, because that suggests that at least some people at the FBI still have their soul.
There are hundreds of thousands of documents being reviewed by probably a thousand or more FBI agents. There is zero chance they are all loyalists.