A ninety-day log of every app's background microphone use is not something an iPhone backup carries. The only microphone record iOS keeps is the App Privacy Report, and it reaches back seven days. Anyone can look at their own device under Settings, Privacy and Security, App Privacy Report: it lists which apps used the mic, when, and which domains they talked to. No keyword cache and no three-month history exist in that file. Worth checking before sharing the prompt, since that report is the part nobody has to take on trust.