i was trying to disable rift spawning in the overworld untill a specific gamestage is obtained, but it seems that rifts from midnight are unaffected even if those should be considered as entity, i'm able to spawn them with /summon.

example spawn.json:

{
"dimension": 0,
"mob": "midnight:rifter",
"result": "deny"

},
{
    "dimension": 0,
    "mob": "midnight:rift",
    "gamestage":"riftOpeningStage",
    "result": "allow"
},

{
    "dimension": 0,
    "mob": "midnight:rift",
    "onjoin": true,
    "result": "deny"
}

rifters will not spawn, however rifts will still spawn.