Apple’s always on watch has a declared 15 second buffer for live audio, and a worse scenario of summarizing your conversations for later but.. they tell you about it proudly. They also tell you how they’ve managed to do it while keeping privacy focused.
It’s your choice if you believe them or not, I like Apple and I wouldn’t use that feature.
The pretending that this is the same thing, that Apple is sneaking something past you when they’re showing you that they’re trying to do it right is a bad faith argument.