Based on the sample app "BlazingCoffee" (where you can reproduce this bug), when I add a ContextMenu in the grid Sales, using OnRowContextMenu of TelerikGrid, there's an asynchrony in the behavior of telerik-blazor.js when it open the popup of the ContextMenu and when it try to focus it.
The bug consists in the fact that when I have a vertically long grid, with an active scrollbar, if I right-click on the first row to open the ContextMenu, the app first try to focus it, does not find it, then scroll the page to the bottom and after all this it open the popup of the ContextMenu in the right position. So you need to scroll back to row where you right-clicked to visualize the ContextMenu.
In general, it try always to focus to the first element of the ContextMenu and after that it open the new ContextMenu in the right position, letting it focus the page in the wrong position.
To solve this wrong behavior I deleted the last line of code of the method "focusFirstMenuItem" of "telerik-blazor.js". If I remove "t&&t.focus()", the ContextMenu works perfectly, without unwanted scrolling.
I hope you can resolve this soon.
P.S. Telerik version: 2.24.0