Well, there's a tiny chance you might find it in one of these lists or similar lists.
https://itch.io/games/genre-platformer/genre-puzzle/platform-web/tag-pixel-art/y...
https://itch.io/games/genre-platformer/genre-puzzle/platform-web/tag-pixel-art/y...
It's only like 200 games, but of course we would not know, if that game uses those tags. Also, there were still flash games back then https://itch.io/games/flash/year-2019