401 errors are causing soft 404 warnings in google console

The aim of the Yoast SEO: Search Index Purge plugin is to purge attachment URLs from the search index by making all of your website’s attachment URLs return an HTTP 410 (content is gone) status. Google has approved of our method to solve this issue in the fastest way possible.

That being said, Google Search Console may notify you of an increase in crawl errors. This is to be expected when a large quantity of previously indexable URLs suddenly return 410 status codes. You do not have to do anything and Google will eventually drop the attachment URLs from the search results since they don’t exist anymore.

After six months the attachment URLs (410 crawl errors) should be gone from the search results. At that time, you should remove the search index purge plugin and keep the redirect setting of the attachment URLs set to “Yes”.