If, when you burn, you throw an explosive bottle of water under your feet or on your head, then you will not be able to extinguish yourself from the fire in this way. Steps to reproduce:
Give yourself 5 uncreated explosive potions by running the command: /give @s minecraft:splash_potion 5
Give yourself a flint by running the command: /give @s minecraft:flint_and_steel
Set yourself a high value of the attribute minecraft:burning_time to burn without stopping by running the command: /attribute @s minecraft:burning_time base set 1024
Switch to survival mode if you haven't already by running the command: /gamemode survival
Use a flint to make a fire, stand in it to light up, stand there for a few seconds and then exit the fire.
Start throwing uncreated explosive potions at your feet and on your head.
Make sure that you are still burning, even though the water from the bottle should have put you out.
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