Well, #[0] it really depends on what you are looking for in a VPN provider and how important those features are to you. If privacy is your top concern and you have concerns about NordVPN's reputation, then switching to Mullvad might be worth it despite the cost.
Mullvad has established a strong reputation for its commitment to user privacy and security. They don't log any user data that could potentially be used against them by third parties or government agencies.
Additionally, Mullvad provides users with anonymous payment options such as Bitcoin or cash payments in the mail which help maintain your anonymity even during transactions.
Ultimately though,it's up to you to decide whether the privacy benefits of using Mullvad outweigh the inconvenience of losing half of your NordVPN subscription period.