What's interesting is that my 2020 TRD Pro does not either (and just assumed it did not have a TPMS reading for the spare tire).
I wonder if it's an artifact of the change over to the different tires and wheels as these vehicles come into port. They actually left an o-ring out of the TPMS sensor of one of the front tires that resulted in a persistent slow leak from the day I got the vehicle delivered, so my confidence is not high
.
I plan on upgrading tires pretty soon including the spare (since the stupid highway tire is there), so will see how that plays out then.