Based on the example https://demos.telerik.com/blazor-ui/datetimepicker/overview, on Cancel or Set, the Input gets focused. On the mobile, it causes the keyboard to appear as well, which is not an intuitive behaviour.
Is it possible for this behaviour to be removed?
This behavior is OS specific, in our tests iOS does not exhibit it. It is generally up to the OS to show the soft keyboard and the web app should not be able to alter that.
Also, generally speaking from an accessibility point of view, popups must have a default focus (we do that), and when they close, they must return the user to the flow of the application in the place where they took it from. In this case, that's an interaction with the picker component.
Nevertheless, if the focus went to the button rather than the input, it is highly likely that the behavior would be resolved. The only downside would be that Android users will need a second action to get the focus back in the input.