OnInitializedAsync is essentially a constructor in blazor. It should only be fired once. Try adding something like:
protected override async Task OnInitializedAsync()
{
//.... your other code
Console.WriteLine("Component Initialized");
}
Then watch your browser console (if WebAssembly) or command line (if Blazor Server) to see how many times "Component Initialized" is printed out.
If it is printing out multiple times, then maybe the Telerik grid is somehow forcing a full page reload?