Google's John Mueller said that spammy links to your site would not be the cause of soft 404 errors being displayed in Google Search Console. Honestly, I've never heard of this theory before, so it is new, and I figured I would share it. But I do not fully understand why someone would think spammy links would cause soft 404s....
-
Google: Spammy Links Do Not Cause Soft 404 Errors
seroundtable.com