Feedback has been a useless measure for many years and the decline in those who leave FB has been longstanding.
The FB percentage displayed is not use by Amazon to rate sellers so is considered less important than potential negative PR if it was removed or fixed.
Sellers are measured by their ODR which is based on multiple factors and as a percentage of sales. ODR is less unfair.
This is not a dying venue, but many sellers can no longer succeed on this venue. They will be gone and the venue will continue to thrive.