Ah, ok. Hmm, interesting question. After quickly checking the feature in a Demonstration environment, my belief is the list does not have a limit (once you expand it to "All activity") but I have reached out to our developers to confirm.
My second hunch is that this list could be affected (shortened) if there's a maintenance performed on the environment to trim some of the repository history (repository logs) but, as mentioned above, I'll work to confirm.
