I noticed a change in the past month or so in the behavior of data binding values when using an inline RenderFragment with the DialogService.
The data binding works as whatever value the user types into the textbox is persisted, but the textbox display value is reset to the original value whenever the focus of the control is set.
See this playground example:
Playground | Radzen Blazor Components
Click the button to open the dialog, type a value in the textbox, click anywhere else within the dialog to see the textbox value reset. Clicking the ok button to close the dialog. You can see that the data binding works as the new value is presented in a dialog alert.
I have observed that this only happens when an inline RenderFragment is used, when the component overload is used it works fine.