My guess is that it's from their SSR framework (ie. remix), which serialized way too many things and sent it to the client. That, and they're using the same feature flag project/config as their main app, because looking at the feature flags it's clearly to do with their main app (ie. AI voice training) rather than this AI voice guesser app.

> "successEnterReferralCodeDuringOnboardingBody": "You've just unlocked 10% off your BoldVoice subscription, thanks to [firstName]'s referral!",