I have no idea if this is relevant, but this sounds exactly like something I was running into for a while until I fixed my trackpad settings on a laptop that had one that was particularly sensitive and poorly positioned. With my preference to click on tap, it would frequently launch the cursor somewhere “random” on the screen, or if I happened to be holding down Shift at the time, to select from where I was to that point, and summarily “delete” everything.
Nothing a simple Ctrl+Z couldn’t fix, but it was super annoying.