Pressing a number while hovering over an item in the Search Items tab in the Creative mode inventory overrides text input

The bug

When in the Search Items tab in the Creative mode inventory, pressing a number while hovering over an item gives a stack of that item to the player in the corresponding hot bar slot instead of entering the number. It also happens while holding Shift since some symbols such as # require a number to be pressed.

Credits

Special thanks to @unknown in this comment for discovering half of the bug.

How to reproduce

1. Press E to open the inventory while in Creative mode, and then click on the Search Items tab.

2. Hover over any item in the tab, and then attempt to enter a # by typing Shift + 3 or a number without holding Shift.
   → ❌ A stack of that item is given to the player in the third hot bar slot instead of the symbol being entered.