The held item tooltip no longer fades correctly

The bug

Prior to 1.14, the held item tooltip used to fade out. This is no longer the case.

To reproduce

1. Switch to an item in your hotbar
2. The held item tooltip will appear
3. Wait a few seconds
   → It will immediately disappear without fading out

Videos

Prior versions: 1.13.2 Tooltip.mp4
1.14: Minecraft 1.14 2019-04-29 00-50-29.mp4