For ANY "our RAG is broken" question, your clarifying volley should hit these four buckets:

Bucket Example question
Define the failure What does "bad" mean? Wrong answers, missing answers, slow, format issues?
Scope it What % of queries? Since when? Specific query types?
See it Can you show me 3–5 failing queries with expected vs actual?
Context Who's using it? Corpus type? Stack you're using? Eval in place?