Thanks Wayne, yes indeed it's an old panel.That's an old panel. I would think if there were an 80A branch breaker limit for a panel like that, the label would explicitly say so. Perhaps @Vines would know. Maybe at the time that that label was printed, the breaker types listed only went up to 80A, so there's an implicit 80A limit.
Otherwise, I don't see why Tesla wouldn't use a 100A branch breaker and a 100A feeder.
Cheers, Wayne