Tag negation

Tags are useful for attributing behaviour to blocks, entities, biomes etc, but when you want to target all biomes in the overworld, except for one, you need to list out every biome except that one.

Instead adding negation to tags, like you can with item components would not only reduce the number of entries in the tag, but also help mitigate mistakes such as missing a biome. 
eg:

{
    "values": [
        "#minecraft:overworld",
        "!minecraft:deep_dark"
    ]
}