After the latest accessibility improvements available with R1 2023 of the KendoReact library, the aria-required attribute is missing in most of the DropDowns.
The aria-required attribute should be rendered in the DOM once the MultiSelect definition contains a required attribute like this:
<MultiSelect required data={sports} onChange={onChange} value={value} />
Title basically says it all. Issue can be easily observed in the basic Multiselect with virtualization example:
What seems strange is that I cannot reproduce this issue with the combobox virtualization, although I found a somewhat similar bug submitted for the combobox - https://github.com/telerik/kendo-react/issues/1450