Your game does not even fit in my browser when I set my browser zoom to 100% and put the browser itself in fullscreen to hide the tabs and clutter. Let me guess. Your windows desktop zoom is set to 100% or 125%.
You should never count pixels of actual display, because you never work on actual pixels, except when getting direct access to the screen. It is always scaled. My screen could handle about 2000 pixel in height. Yet my browser would tell your game, should it ask, that is has window.screen.height = 720 and this is not even factoring in the zoom level of the browser. And I double checked. This is the recommended setting of windows display setting.
Issues like this are usually dealt with by clicking the fullscreen button. No scrolling to the exact point that it fully fills the screen, no accidental offscrolling, no wasted pixels, also no clutter like tabs and status bars.
So as a player naturally I would expect those game engines to be super developer friendly for basic stuff like that. Guess this is not so.
What you need is an aspect ratio and an idea how big the user interface elements have to be to be of use, in relation to the full display size. Also I randomly picked a 5 year old huawe spec, a p30 has this resolution: 1080 x 2340 pixels, 19.5:9 ratio. You have over 2000 pixels on that device in height. Guess you are working on a viewport there too.