With the Fabric API and Vanilla enchantment filter, the world opens in Safe Mode.

[Antoha256M]

The game version is 1.21.8, only the fabric api version 0.129.0 is installed.

There is only one datapack in the world, here is its content:
Ench-Filter-Test > pack.mcmeta —

{
    "pack": {
        "description": "by §6Antoha256M",
        "pack_format": 81,
        "supported_formats": [
            48,
            83
        ]
    },
    "filter": {
        "block": [
            {
                "namespace": "minecraft",
                "path": "enchantment"
            }
        ]
    }
}

Another thing I noticed during the tests is that if you don't specify the namespace, there will be no safe mode.

{
    "path": "enchantment"
}

But the goal is to disable only vanilla enchantments.

I also attached a log with the launch of the game and the entrance to the world.
latest.log

[Apollounknowndev]

This doesn't validate in vanilla, either. Required tag entries being missing causes datapacks to fail to validate in 1.21.6+, meaning you must remove all enchantment tags (both minecraft and c-namespaced ones).