It is definitely capped, here is some proof:
I switched my monitor to 120Hz and I scrolled fast through the Start11 settings menu by dragging the scrollbar with the mouse and I used OBS to record the screen at 120fps
Here is the result zoomed and slowed down to 1%, as you can see the cursor moves on every frame but the Start11 UI updates every other frame
And here scrolling through the Windows 11 settings for comparison, both the cursor and the menu are moving on every frame
