Hmm, I'm not hearing this on my end - is this in Mandarin or Cantonese? And you're quite sure it's *not* the system voices? Does it happen regardless of where you play them from (dictionary, flashcards, reader, etc)?
Upon further inspection, I don’t hear it on my iPhone, only on the iPad Pro (13-inch, M4, 18.1). It happens in flashcard mode with the respective TTS voices.