One can filter out data with filters, but also by mean of the "Limit data with Expression" in the property box of a vizualisation. In that case, the number of rows that is displayed at the bottom of the screen is not correct: it takes into account only the number of lines that were eliminated by the filters. This is confusing for the end user, because the real number of lines that were eliminated also includes those which were eliminated by the limiting data expression.
Both information can be interesting, but I agree this is confusing. A similar thing happens if you use Ctrl-A to mark all filtered rows. Data limiting is also not taken into account there, which I find even more confusing (see TS-I-7052)