Poor search quality over semantically equivalent searches

Versions (relevant - OpenSearch/Dashboard/Server OS/Browser): 2.17

Describe the issue:

The hybrid search query returns significantly different results for searches which are semantically identical.

Configuration:

Relevant Logs or Screenshots:
Using hybrid query on OpenSearch with knn_weight == 0.7 and bm25_weight=0.3 leads to different search results. I show different references with a, b, c, d, e.

query: Why is the sky blue

results: [a, b]

query: why is the sky blue?

results: [c]

query: Why the sky is blue

results: [b, e]

query: why the sky is blue?

results: [c]

query: What is the reason that the sky is blue?

results: [b, f]