Before 1.13:

• Press F1 to hide the HUD.
• Press T or / to enter the chat input box
• The entire HUD becomes visible (including chat messages)

After 1.13:

• Press F1 to hide the HUD.
• Press T or / to enter the chat input box
• The input box is visible, but messages are hidden.

This might have been intentional, but I think it's inconvenient and pointless. What's the point of being able to use chat/commands if you can't see any messages/command output?
When taking screenshots without the HUD, I normally press F1, then F2, then open chat to click the link. But now I need to press F1 again after taking the screenshot, in order to see the file link.