The new Siri will offer auto-deleting transcripts:

According to Bloomberg’s Mark Gurman, the more chatbot-like Siri set to debut in iOS 27 will include the option to autodelete chat histories. Users will be able to save conversations for 30 days, one year, or forever.

It’s a trade-off. A short history will make for a slightly worse product. I feel like Apple is still catching up to where the tech was two years ago.