https://blazorrepl.telerik.com/QwFOPdYV18zmbgUK59

In this REPL demo select the splitter and then slightly move the mouse left and right or up and down and the slitter will move itself all the way to the left without the mouse going there. So this also means that if you slowly move the mouse to the right the splitter goes to the left.

It happens in all the browser I tested which include Firefox, Chrome and Edge.