A pointer reaching the screen edge can activate a hot corner while you are aiming for another control. If you still want the action available, make it require a modifier key. That separates ordinary corner movement from an intentional shortcut.

Open System Settings, Desktop & Dock, then Hot Corners. Identify the corner that produces the unexpected action and note its current assignment before changing it.

Add a deliberate keyboard condition

Open that corner’s action menu while holding Command, Shift, Option or Control; Apple also permits combinations of these keys. Choose the intended action with the modifier held, then click Done.

Pick a combination you can comfortably hold while moving the pointer. Keep the purpose clear: the corner should respond when you deliberately use the combination, rather than during an ordinary sweep across the desktop.

Test both cases

Move the pointer away from the corner, then return without the modifier. The configured action should not trigger. Move away again, hold the chosen key and return to the same corner. Confirm that the intended action occurs.

Use an action and test moment that will not interrupt unsaved work or a presentation. If the assigned action locks the screen, be ready to unlock your own session before testing it.

Repeat the pointer movement that previously caused trouble. This checks the actual interaction rather than only proving that the settings window accepted a choice. If it remains awkward, return to Hot Corners and reconsider the assignment.

On a shared Mac, tell the other person which corner and modifier you changed. A small, documented condition can preserve a useful shortcut without leaving the next user to guess why the corner appears unresponsive.

References: Apple: Hot Corners.