LATENT FOCUS
Ah! Seems like there may be a bug? I'm using Medium Size, Show 75. Have a big tall screen like yours.
I noticed the Icon area opens a BIT slowly / closes, too. No problem. BUT...it seems the LINK to the apps remains on the screen after it is closed. So that, though I am clicking on the screen / currently running app, the AREA is the same as an Icon when the Start11 panel is open. So, the app for that icon...starts.
Out another way - though the S11 screen is closed, a phantom set of tiles PERSISTS, and if you click in that area, an app will start.
Older machine, yes. BUT! LOTS of Ram & physical memory. Win 10.
What do you think is happening?