Yes your original point was well made. It just wasn’t clear yet how DNS requests would leak search queries. So more precisely, multiple DNS requests with local cache misses in a short period of time can be used to infer search queries. Like if there are DNS requests for google, amazon, and a botany supplier one after another, then it could be inferred that you searched for something related to shopping and plants.
Thanks for the detailed response!
As a software dev myself, I must say with all due respect that devs are not known for their intuition.