"Inheriting" an SEO penalty

One of my sites was badly hit during the December update and it seems to have fallen out of Google's favor (losing rankings and authority).

I ran an audit and I realized I have hundreds of links from a pretty authoritative site (we had a business relation) which however lost almost 90% of their traffic and rankings during the same period.

I suspect these two events are connected so I would like your opinion on this: is it worth it for me to disavow all/most of those links or it won't make any difference?