This applies specifically to using multiple monitors/windows; when Rider itself does not have focus at all, there are no tooltips. (That could be an issue too but not exactly what I'm reporting). (This is 2023.2.3.)
Basically, if you have more than one Rider window and hover the mouse over a window that does not have focus, the tooltips are wrong. (It is required that at least one of the Rider windows has focus for this to happen.)
You can tell from the tooltips that it is using the focused window instead of the hovered window to get the data for the tooltip. You do only get tooltips when you hover over actual code elements in the unfocused window, and not from whitespace in the unfocused window, but the tooltip contents are from code in the focused window instead.