The final debate was Oct 28th 1980 - 24 years ago today! It was the “There you go again” debate, just 7 days before the election. It is a reasonable read of history that people broke late for Reagan, not that the polls were fixed.
The “tell” that there was no “late break” was that some early polls (before the debate) had Reagan way ahead.
Look at the wild variation between polls in October.