Realm Database initialisation in the app with migration issue from 4.4.0 -> 5.3.0

Database.swift

class Database: NSObject {
    
    @objc static let shared = Database()
    
    private let schemaVersion: UInt64 = 1 // In the prod version this value was incremented.
    
    static var realm: Realm? {
        do {
            let realm = try Realm()
            return realm
        } catch {
            print("Realm could not access database: ", error)
            return nil
        }
    }
    
    func setup() {
        Realm.Configuration.defaultConfiguration = Realm.Configuration(schemaVersion: schemaVersion, migrationBlock:  { [weak self] migration, oldSchemaVersion in
            guard let `self` = self else {return}
            // We haven’t migrated anything yet, so oldSchemaVersion == 0
            if (oldSchemaVersion < self.schemaVersion) {
                // Nothing to do!
                // Realm will automatically detect new properties and removed properties
                // And will update the schema on disk automatically
            }
        })
    }
}