Clicking "Leave server" after dying on hardcore multiplayer does not disconnect you from the server

When you are on a server with hardcore=true, there is a bug with the "Leave server button".
How to reproduce:

1. Die on hardcore mode enabled server.
2. Click "Leave Sever"
3. Go to singleplayer, multiplayer or realms menu.
4. Hit Esc.

Expected result

You will be disconnected from the server and couldn't go back in the server without navigating the multiplayer menu.

Actual result

You will reappear on the Server death screen with the choice of leaving or spectating the world again.

Video demonstrating this issue by [Helper] Johnibur 2019-05-30 01-23-26.mp4