Ever since I updated GameMaker to v2024.14.3.260, maximizing the game window leaves a gap at the top, exactly the amount of a windows taskbar. The same happens when dragging it to the top of the screen to maximize. It doesn't happen on builds prior to this version.

Hard to tell, just loaded my test project in IDE v2024.14.4.221 Steam / Runtime v2024.14.4.265 and the window seems to maximize fine, be it through the function or clicking the button.

Thank you SirDude! I was googling how to fix this "window gap" issue when maximizing the game and ended up here. 2024.14.3.260 was the issue as you suggested, doing my Windows builds now with 2026 LTS and window fills the screen now nicely.