What kind of underlying framework/ engine gives you scrollbars for the actual game area?
Is this html?
The reported resolution of the Desktop is not the actual resolution. Windows is zoomed for "higher" resolutions. The recommendation is 150% for 1920x1080 displays. So your browser/game might get reported a relative resolution. Also a browser might have a base zoom that is higher than 100%. I see problems on fullscreen web games all the time, so there might be some common pitfalls.
On user end I usually have this custom css active, so I actually do not know, if some of those games would display scrollbars. There is this kinda bug, that sometimes scrollbars are displayed for the space they would take. Meaning, scrollsbars would not be needed, if there were not there. But since they are there, they take up space from the area, making scrolling necessary.
element::-webkit-scrollbar {
display: none;
}
::-webkit-scrollbar {
display: none;
}