This is barely three weeks. But just like games can go viral, they can go the opposite direction. If I were to take those numbers seriously, there is a downwards trend visible starting from peak of oct 25. You can draw a line from there to now that points downwards, with yet another peak in between on nov 5.
To speculate, your game got a boost somehow. Does not matter from where. But after that boost wore off, the "natural" visitor numbers are more near to 1k than to 4k. There is also a limited number of people visiting itch - compared to a service like steam. It could just be that your potential players in the currently existing user base is exhausted in the meaning of, most people that might be interested in your game already visited your page. Or at least, enough to now have a dwindle in visitor numbers.
I remember your game. I visited your page in the middle of september according to my browser history. Not my cup of tea. But do not ask me, how I found it. I can only tell, it was not via popular browse, as I bascially never use that feature.
As leafo iterated above, you need to advertise your stuff outside of itch. Being on the popular browse page is in itself not enough to stay there.