Since 1.14, hotbar item text no longer fades out after being selected. In versions prior to 1.14, the hotbar text of the item would fade out after the item had been selected. In 1.14, no such transition is present. The text disappears without any transition.
The attached screenshot displays the item text fading in the hotbar in 1.13.2.
Thank you for your report!
We're actually already tracking this issue in MC-150242, so I resolved and linked this ticket as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature in the future to see if the issue has already been reported.