John Mueller even said himself: https://twitter.com/johnmu/status/913222203071594496

This is not an isolated thing, negative SEO attacks happen on a daily basis, mostly intention but I bet you there are some accidental ones too.

If neg SEO still worked efficiently, then SEO's would be focusing on spamming their competition instead of investing in quality content and backlinks.

Like any case, disavow the links if you need, then move on and continue to build content Google likes with quality backlinks.