Havi

Would it be possible for you to provide a log of the launcher?

You can find the log by going to: AppData\Roaming\.minecraft and then launcher_log.txt

Was this done on a Multiplayer Server or in your Singleplayer World?

Maybe an idea to upload a log file.

I'm sorry Jeramy, but you need to understand that the report you currently have made is not useful. No logs, nor information are provided for the developers to look into.

I highly recommend you to get some kind of log and upload it for the developers to look at. If that is not possible, then you might want to close out this issue.

Confirmed. The same thing is happening to me.

Pressing ESC and then Back to the Game does not work on a Multiplayer Server. Reconnecting is required to get it to reappear.

You probably have Mending on your Pickaxe. If you have Mending on your Pickaxe and the Pickaxe is damaged, all the XP goes to the Pickaxe. If your Pickaxe is fully repaired while Mending is applied, all the XP goes to the XP bar.

Tested it and works as intended.

Yeah, now Gold Farms are completely ruined. There was no need to touch Zombie Pigmens. They worked just fine and now also Zombie Pigmens are less challenging and I really like that part. Whenever you hit one of them, they all come after you

It works as intended. I know why you thought this was broken. It can take up to 5 minutes for the Zombie Villager to turn normal. 

I was able to reproduce this.

I did some tests to make sure that it isn't any specific Slow Falling potion doing this. It's doing it for all of them.

Potion of Slow Falling (1:30)
Potion of Slow Falling (4:00)
Splash Potion of Slow Falling (1:30)
Splash Potion of Slow Falling (4:00)
Lingering Potion of Slow Falling (0:20)
Lingering Potion of Slow Falling (1:00)

Unable to reproduce this. Are you sure there was nothing else running in the background (maybe updates) while this happened? Are you able to reproduce it all the time on your end?