@Skites2 This reason is common in the field of SEO backlinks, but what to do to prevent is try to go to every spam link and delink your site from it, if quantity of these spam links are not very high. other than that still google hasn't able to identify spam links and prevent sites from dropping your DA. Focus on getting high authority links instead to get back your DA.
Similar case happened to this site https://liaiseplatform.com/ and they lost all their DA rating, they had to go manually to every site to delink from them