No. Audiences does not hurt deliverability if used correctly.
Audiences applies extensive email validation, which involves validation against numerous highly trusted email validation services to minimise bounce rates and maximise deliverability.
We also filter emails to prevent disposable, role-based, or risky emails from being provided to your Klaviyo account. Any net new profiles we provide have also exhibited active purchasing intent somewhere across our entire network, ensuring that emails belong to active, real and high quality contacts. This results in our bounce rates to be lower than Klaviyo averages across our merchants.