It was this account, I only have the one. I got the "You're posting too fast. Please slow down. Thanks." error last month when I hadn't made any more then a few replies, and not in quick succession.

I got the error after writing out a detailed reply (which I lost as a result since the error is on posting not loading the form) so I couldn't have been fast enough to trigger a regular rate limit.

I thought it was unusual so I searched and found your explanation for this error message https://news.ycombinator.com/item?id=35157524

I assumed since I've had two warnings, a rate limit was applied.

Although given Anthropic have since removed the word "understands" from their page, I feel I was vindicated of flamebaiting. [1]

[1]: https://news.ycombinator.com/item?id=45722979