I’m not certain if this is an AnkiHub problem, or a personal problem with my collection. Nonetheless, the new feature in the browser appears to be showing me notes that have been updated over the past several days instead of notes only updated today. I manually sync with AnkHub so I feel that I have an idea of the number I should be seeing.
I recently had to install the “fix invalid card ID” add on, which I believe is related to incorrect dating; however, when I go to Today::Added, the number of notes presented is accurate, so I think that this is an AnkiHub issue.