Your Amazon preview sounds different from others: it’s like a skype telephone-call , (no voice signal above 6kHz).
The other Amazon previews have voice up to 10kHz , (most people can hear up to ~14kHz) …
A possible explanation : your notch filter to deal with sibilance (“s” sounds) has amputated everything above 6kHz.
If that’s the case you need a De-Esser instead of a notch-filter.
An easy to use De-Esser plugin for which works with Audacity on Windows be had for less than US$5.
A slightly better De-Esser plugin can be had for free for 30 days only.