Gorm Unnecessary ALTER TABLE during migration

Description

Here's my model

type SalesOrderItems struct {
    ID            uint      `json:"id" gorm:"primaryKey"`
    ItemId        uint      `json:"itemId" gorm:"not null;uniqueIndex:unique_soi;"`
    OrderId       uint      `json:"orderId" gorm:"not null;index:combi_soi_order_license_idx;"`
    LicenseId     string    `json:"licenseId" gorm:"not null;index:combi_soi_order_license_idx;uniqueIndex:unique_soi;"`
    ProductId     uint      `json:"productId;" gorm:"not null;"`
    Quantity      float32   `json:"quantity" gorm:"scale:2;not null"`
    NetPrice      float32   `json:"netPrice" gorm:"scale:2;not null"`
    Discount      float32   `json:"discount" gorm:"scale:2;default:0"`
    BaseDiscount  float32   `json:"baseDiscount" gorm:"scale:2;default:0"`
    PurchasePrice float32   `json:"purchasePrice" gorm:"scale:2;default:0"`
    Tax           float32   `json:"tax" gorm:"scale:4;not null;"`
    CreatedAt     time.Time `json:"createdAt" gorm:"not null;"`
    UpdatedAt     time.Time `json:"updatedAt" gorm:"not null;"`
}

When I run the migration during start up db.DB.AutoMigrate(models...) where &SalesOrderItems is an element of models gorm always executes a ALTER TABLE command on the discount column and tries to set it to 0.0000.

the default value is already set
the table is enormous and that command shuts down the whole DB ... as a workaround I had to exclude this table from the auto migration

Gorm Unnecessary ALTER TABLE during migration