Mullvad VPN has announced that it will no longer support port forwarding due to frequent abuse of the feature. While port forwarding adds value for users who need to allow friends or family access to services behind the VPN, it has also been used to host malicious content, resulting in law enforcement contacting the company, IP blacklisting, and cancelled hosting providers. Existing ports will be removed by July 1, 2023, and users with active ports will be directly affected. Mullvad VPN urges its users to update their services accordingly and ensures that those who do not use port forwarding will not be affected by this change.
https://mullvad.net/en/blog/2023/5/29/removing-the-support-for-forwarded-ports/