Why Json Unmarshall changing array type in Golang?

I'm trying to seed my Postgres database as functionally. In my case, SeedSchema() function can take any type struct. So I define a interface and create functions to my structs which will seed. I tried with generics and without.

When I unmarshall any json array from file as byte array, json.Unmarshall method change my tempMember member of struct. Exp, models.Term to map[string]interface{}. I've used unmarshall before this function and I've not seen like this situation.

Here is my SeedSchema() function:

func (db *Database) SeedSchema(models ...globals.Seeder[any]) error {
var (
	subjects []globals.Seeder[any]
	fileByte []byte
	err      error
	// tempMember any
)
if len(models) == 0 {
	subjects = seederModelList
} else {
	subjects = models
}
for _, model := range subjects {
	fileName, tempMember := model.Seed()
	fmt.Printf("%+v\n", reflect.TypeOf(tempMember)) //1
	if fileByte, err = os.ReadFile("db/seeds/" + fileName); err != nil {
		fmt.Println(err)
		return err
	}
	if err = json.Unmarshal(fileByte, &tempMember); err != nil {
		fmt.Println(err)
		return err
	}
	fmt.Printf("%+v\n", reflect.TypeOf(tempMember)) //2

}
return nil 
}

First print returns []models.AirportCodes and the second []interface {}.

Here is my interface and model:

func (AirportCodes) Seed() (string, any) {
	return "airport_codes.json", []AirportCodes{}
}

type Seeder[T any] interface {
	Seed() (string, T)
	// Seed(*gorm.DB) error
	TableName() string
}

seederModelList = []globals.Seeder[any]{
		m.AirportCodes{},
		m.Term{},
	}

After a few weeks, I have looking for solve this problem and look unmarshaler interfaces and examples. Then Like what icza said, I started to look over the my code that convention between types and I solved like this. If you guys have better answer than mine, please add answer.

Data:

[
    {
        "id":1,
        "name":"Term 1",
        "content": [
            "a1",
            "a2",
            "a3"
        ]
    }
]

Result:

[{ID:1 Name:Term 1 Content:[a1 a2 a3]}]

UnmarshalJSON Function:

func (term *Term) UnmarshalJSON(data []byte) error {
	tempMap := map[string]interface{}{}
	if err := json.Unmarshal(data, &tempMap); err != nil {
		return err
	}
	*term = Term{
		Name: tempMap["name"].(string),
	}
	if tempMap["content"] != nil {
		for _, v := range tempMap["content"].([]interface{}) {
			(*term).Content = append((term).Content, v.(string))
		}
	}
	return nil
}

Thank you for comments.