In versions of Telerik.UI.for.Blazor v2 all the way up to v2.30.0, the NumericTextBox, when provided a Min and Max would display an indication that a number is out-of-range by marking the input as invalid while the focus remained within the input.
After upgrading to v3, the invalid indication no longer happens.
In the attached example project, you'll find that using v3 NumericTextBox with Min=0 and Max=5, does not indicate invalidity if you enter "9" for instance. The input just snaps to 5 when the input loses focus.
If you instead use v2.30.0, it will show the border of the input in red when entering "9".