Virtualize compnents adds and removes placeholders in an endless loop

[Liero]

Describe the bug

After upgrade to .NET 6 I see constant rerenreding of virtualize components. Placeholders being added / removed in a loop.

To Reproduce

1. Go to: https://blazorrepl.telerik.com/mFllvCvR20mo56iv20
2. Scroll down couple of times
3. In developer tools, you can see the rerendering

The issue is much worse in Blazor Server side

Code:

@using Microsoft.AspNetCore.Components.Web.Virtualization;
@page "/"
<style>
    .grid-cell {
    display: flex;
    height: 50px;
    border-bottom: 1px solid;
    box-sizing:border-box;
}
</style>


<div style="height: 500px; overflow: auto">
    <Virtualize TItem="Item" ItemsProvider="GetItemsAsync" OverscanCount="0">
        <ItemContent>
            <div class="grid-cell" data-row-index="@context.id" @key="context">
                @context
            </div>
        </ItemContent>
        <Placeholder>

            <div class="grid-cell my-placeholder">
                Placeholder @context.Index; Height: @context.Size
            </div>

        </Placeholder>

    </Virtualize>
</div>

Further technical details

• ASP.NET Core version 6:

dotnet --info Output

.NET SDK (reflecting any global.json):
 Version:   6.0.100
 Commit:    9e8b04bbff

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.22000
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\6.0.100\

Host (useful for support):
  Version: 6.0.0
  Commit:  4822e3c3aa

[mkArtakMSFT]

Thanks for contacting us. This is a dupe of #38439

[Liero]

The fix is to set Oversize Count to a larger number. Usually 3 is enough