I suspect these are not related to your use of Tor. Note that jgrahamc is at Cloudflare, not HN, and was asking about the Cloudflare interactions people on Tor are having, as the CAPTCHA the OP is speaking about is implemented by Cloudflare.
I am currently rate-limited, I have been on rate-limiting before, and I've had my rate-limiting disappear. This has more to do with how happy (or unhappy, as the case is) the mods are with your commenting habits than what browser you are using. I do not know if your rate limit penalty has an expiration date or if they manually remove you, HN mods rarely if ever discuss rate limiting, but it is almost surely to curb what HN mods consider poor quality comments and ensure they don't overwhelm a discussion.
It's not so uncommon that we discuss rate limiting. We do that all the time when people email us and I've posted not infrequently about it: https://hn.algolia.com/?sort=byDate&dateRange=all&type=comme.... People are welcome to ask questions, though as the site guidelines ask, it's better to do that by emailing us.
Being rate limited is annoying, so I appreciate the even-handedness in what you wrote.
I am currently rate-limited, I have been on rate-limiting before, and I've had my rate-limiting disappear. This has more to do with how happy (or unhappy, as the case is) the mods are with your commenting habits than what browser you are using. I do not know if your rate limit penalty has an expiration date or if they manually remove you, HN mods rarely if ever discuss rate limiting, but it is almost surely to curb what HN mods consider poor quality comments and ensure they don't overwhelm a discussion.