Hey @HLosfelt there is only a single subscription page per HubSpot portal right now, as far as I know there’s no way to have multiple subscription pages for multiple brands on a single portal. There’s some more information on how to change your subscription template here.
In HubSpot, the unsubscribe link is tied to your email subscription preferences page, which is hosted on a specific domain you’ve connected to your account (usually something like email.yourcompany.com). You probably want the unsubscribe link in those emails to reflect that domain without messing up the existing one tied to your original domain.
Make sure your new domain is connected in HubSpot under Settings > Website > Domains & URLs. Then, go to Settings > Marketing > Email > Subscription Types this is where you manage the subscription preferences pages. You can either update the existing one to be hosted on your new domain or create a separate version that lives on the new domain. Once that’s done, make sure any emails sent from the new domain use an email footer that links to this updated preferences page.