Changing one word in question, changes the top chunks picked up?

Prompting
1

Question: how to create google account?
Chunks are picked up properly and response is generated.

Question: how to create a google account?
[same question with one word -‘a’ ]

  • The chunks picked up changes and got a response ‘not sure.’
    Is it a case that adding a letter ‘a’ would change the entire input embeddings.