When trying to drag/resize the splitter to the sides on a touch screen, you are only able to move the splitter a little bit before the whole screen starts moving.
To reproduce, go to the splitter demo (Blazor Splitter Demos - Overview | Telerik UI for Blazor), open the inspector, and change the view to a mobile device. I tested specifically on the iPad option.
I've tested the behavior on an Amazon Fire 10, One Plue 8T, and a Google Pixel 4, and all 3 of them have displayed the behavior. I also tested on a 7th gen Ipad (in safari) and found the control did indeed work as expected there.