Dock moves to other screen too quickly

My MacBook is attached to an external display. This display is my main display and it should always show the Dock (at the bottom).

Before Big Sur, the Dock would only move to my MacBook when I put my mouse pointer at the bottom of my MacBook screen for about a second. Which was fine.

Since Big Sur, my Dock is moving from my external display to my MacBook much more often. Usually when I'm hovering above my Dock on my external display. So nowhere near the bottom of my MacBook display.

Any idea why this is happening? It happens on different Macs, it's surely BigSur related.