It has been specifically called out as its own rule which is in addition to normal movement. So the jump distance and your normal speed are almost unrelated.
However if your movement speed is zero you simply cannot Rabbit Hop
At higher levels and/or with the Jump spell a Harengon can move very fast and a lot of that movement does not provoke attacks of opportunity, not even from Sentinel feat or similar abilities. Which is why is strictly limited how many times you can use it, the ability is very powerful.