The NBT value of the "Invulnerable" data is reset to the default value after the player's death.

If you use the NBT data editor to make yourself invulnerable by changing the value of the “Invulnerable” data to “1” and then die using the /kill command, then after respawn, the value of the “Invulnerable” data will reset to the default value. How to reproduce:

1. Download the NBT Data Editor

2. Open it, go to the folder with the world, then go to the “players” folder, then go to the “data” folder, and then select the very first one from the list of “dat” format files.

3. In the dat file with your data, find the data value “Invulnerable” and change it to “1”. Then save the change you made. You can close the editor.

4. Log into the game and use the /data get entity @s Invulnerable command. The value will be “1b". After that, summon the ravager with the command / summon minecraft:ravager and hit him a couple of times to make sure that you can't take damage.

5. To die, use the command /kill or teleport yourself into the void using the command /tp ~ -999 ~.

6. After respawn, use the /data get entity @s Invulnerable command again. The value will be “0b". After that, summon the ravager again with the command /summon minecraft:ravager. He will be able to deal damage to you.