the following advancement should trigger when a player picks up a bucket of tropical fish with the `BucketVariantTag` set to `67502593`:

{
  "display": {
    "icon": {
      "id": "minecraft:warped_fungus",
      "count": 1
    },
    "title": {
      "text": "triggered"
    },
    "description": {
      "translate": "advancements.husbandry.tactical_fishing.description"
    }
  },
  "parent": "minecraft:husbandry/fishy_business",
  "criteria": {
    "tropical_fish_bucket": {
      "trigger": "minecraft:inventory_changed",
      "conditions": {
        "items": [
          {
            "items": "minecraft:tropical_fish_bucket",
            "components": {
              "minecraft:bucket_entity_data": {
                "BucketVariantTag":67502593
              }
            }
          }
        ]
      }
    }
  },
  "requirements": [
    [
      "tropical_fish_bucket"
    ]
  ],
  "sends_telemetry_event": false
}

However it doesn't work because the components needs an exact match as most naturally caught tropical fish would have a health tag, an exact match can be created with 

/give @s minecraft:tropical_fish_bucket[minecraft:bucket_entity_data={BucketVariantTag:67502593}]

So the modified version should work: 

{
  "display": {
    "icon": {
      "id": "minecraft:warped_fungus",
      "count": 1
    },
    "title": {
      "text": "triggered"
    },
    "description": {
      "translate": "advancements.husbandry.tactical_fishing.description"
    }
  },
  "parent": "minecraft:husbandry/fishy_business",
  "criteria": {
    "tropical_fish_bucket": {
      "trigger": "minecraft:inventory_changed",
      "conditions": {
        "items": [
          {
            "items": "minecraft:tropical_fish_bucket",
            "components": {
              "minecraft:bucket_entity_data": {
                "Health": 3.0,
                "BucketVariantTag":67502593
              }
            }
          }
        ]
      }
    }
  },
  "requirements": [
    [
      "tropical_fish_bucket"
    ]
  ],
  "sends_telemetry_event": false
}

But this too doesn't work as in json the 3.0 of the health tag will be implicitly casted to an int and result in health:3b where as the natural occuring ones will be floats so health:3.0f. In effect this renders them inaccessible for advancements with the recent changes, `minecraft:bucket_entity_data` should be able to check for the tags given not an exact match (which I presume was simpler to implement with "==").

This can be further proven by using a health value that cannot be casted into an integer, such as 2.5, if you change the advancement to trigger on 2.5 health and then spawn a tropical fish with that BucketVarientTag it will work just fine. Unfortunately fish spawn with 3.0 health. Like with this command:

/give @s minecraft:tropical_fish_bucket[minecraft:bucket_entity_data={BucketVariantTag:67502593,Health:2.5f}]

Another way to check this is by giving yourself a fish with interger health with the command below, this will trigger the advancement as it matches the integer 3 for health

/give @s minecraft:tropical_fish_bucket[minecraft:bucket_entity_data={BucketVariantTag:67502593,Health:3d}]

How to reproduce:

1. Add datapack-BucketVariantTag.tag to a world
2. Spawn a tropical fish with the `BucketVariantTag` set to 67502593
3. Catch the fish in a water bucket and that should trigger the advancement but it won't
4. if you use the following command it will as it lacks the health tag "/give @s minecraft:tropical_fish_bucket[minecraft:bucket_entity_data=
   {BucketVariantTag:67502593}

   ]"

5. The same can be done with datapack-BucketVariantTag&Health.tag and the command would be "/give @s minecraft:tropical_fish_bucket[minecraft:bucket_entity_data=
   {BucketVariantTag:67502593,Health:3b}

   ]" 

Expected result:

1. the advancement should trigger when a fish with the "BucketVariantTag" of 67502593 is caught and the health is 3.0

Actual result:

1. the advancements do not trigger be cause the 3.0 is converted into an interger and since "3d" != "3f"

I've attached test datapacks to show these behaviours, one checking for the `BucketVariantTag` another checking for both the tags