1.15.2, 1.16.2, 1.16.3, 1.16.4, 20w45a, 20w49a, 20w51a, 21w03a, 21w05b, 21w06a, 21w07a, 21w08b, 21w11a, 21w13a, 21w15a, 1.17, 1.17.1
1. Open the creative inventory
2. Move the cursor outside of the inventory GUI
3. Start holding the left mouse button
4. Move the left mouse button on a currently not selected inventory tab
5. Release the left mouse button and observe the selected inventory tab change
This behavior is at the very least inconsistent with the visually identical advancements GUI tabs, and in my opinion shouldn't happen at all - clicks should only be registered if the click started and ended on the same UI element. See
MC-110368 for more info on this topic.