Minecraft hard mode can be revived?

I recently created a new Minecraft world in hard mode because it appealed to me that you can die without being revived. I still died after a while and it said REVIVAL and back to the main menu, even though I was playing hard. What can be the reason or how can you change it accordingly, so that you can't be revived, as it is also known?

You have to set the difficulty / game mode Hardcore in the world settings

So with me then it says do not resuscitate.

Which version are you playing? Java?

This is only possible if you create a new world, you can't change that with an existing world

Yes i play on the java

Isn't there also the Ultra Hardcore mode?

No, only as a mod

But you have to adjust this when you create a new world. Are you sure you have set the difficulty mode to hardcore?

Where are the world settings?

Only the level of difficulty is difficult. What you are looking for is the hardcore mode.

There's a revival at Heavy. You have to play hardcore

For me it is difficult and not hardcore

You will likely have to choose hardcore.

The difficulty level before that will be difficult.

Ok and how do i change the mode to hardcore?