Have you noticed through your Google account that there are items being indexed that shouldn't have been?   One for me was taxonomy terms.  Not important to be followed. Being indexed on my sitemap (do I just erase those entries on the XML file?) Being crawled (I am guessing this is with a robots.txt file though I have never created one before) Being viewed (stumbled upon) -> if this even possible to block?   Resolve these quickly by simply adding disallow in robots.txt...

If you are like me you probably have searched for clues to and found little... particularly when confronted by the errors as you unravel how this works.  Okay a slight exaggeration, there are snipets of info that people have solved this annoying issue in  making comments work in Drupal 8 REST services. The lack of collective information in resolving issues has meant hours of debugging and working through core code to understand what is actually happening.  If you want to...