How permanent is a ranking decrease from a bad PBN Link?

If you experience a ranking decrease from a PBN link can you just remove the link and googles algorithms will forget about it in a month or two? Or do you think they keep a history of all sites that have ever linked to your domain? I feel like on their part that would be smart, dosen't seem natural for someone to link out to a site then remove the link a month later.

I am currently in the process of testing this, but since it will take like two months to test I was just wondering if…

How permanent is a ranking decrease from a bad PBN Link?