The mouse is double-clicking instead of a single click.

Clicking the left mouse button once, but the mouse performs a double-click. Or when you try to highlight text, it doesn't get selected. Accidentally closed windows, links opening twice...

The microswitch under the mouse button wears out over time and starts to become unresponsive. Sooner or later, you'll have to replace the mouse. But there is a temporary software solution available.

A simple program attempts to filter out clicks if there is a very small time gap between them. In my case, it only eliminates about half of the erroneous clicks, but that's still a nice improvement. It doesn't require any setup.

https://www.softpedia.com/get/System/System-Miscellaneous/Left-Mouse-Button-Fix.shtml