I think it would happen with any persona that Anthropic chose. I enjoyed the bouncy, optimistic style at first. I've since grown to hate it.

A terse and compliant robotic servant should've been the persona they chose, because that's probably 99% of what those wanting to use it for work expect.

how do they infuse this personality? do they train the human feedback providers with a certain personality?

If we assume the personalities come from human feedback, it would have to be some unholy amalgamation of those feedback providers right?

yea you are right. Maybe they generate lots of sythetic data with that personality an pretrain with it. just a guess.