Search is random and truncated and not browse. You get pages/infinity scroll on browsing for tags and for popular etc.
Try other search terms. There are ones with far over 100 results. But you still will not get an exhaustive result displaying all items. This is intentional, so all relevant results get a piece of the cake at some point. The reasons might be, to discourage search ranking optimisation, as people try to do with regular search engines.
Also, this might be counterintuitive, but you cannot search for tags. If you want to find things with tags, you need to use the other "search box", the tag box. You can enter any tag there, it does not has to be in the list. But someone has to have tagged it.