When the data pack "vanilla" is disabled, water drips lava particles and lava appears as water. As much as I support offloading of Minecraft functionality into customizable data packs, something tells me changing and disabling textures should be left to resource packs.

EXPECTED: Water to drip water and lava to look like lava

WHAT HAPPENED: Both water and lava look like water, but both drip lava particles.

STEPS TO REPRODUCE:

1. /datapack disable vanilla
2. Place water on top of a block
3. Note the lava drips on the bottom of the block
4. Replace water with lava
5. Still looks like water but now it sets your house on fire