Strange Category URLs

[Goedekers]

Some strange URLs began showing up in Google Search Console recently. It looks like several categories are being combined.

The URL in the category tree is:

/appliances/cooking.html

However, these URLs are showing up as 404s in GSC:

/appliances/cooking/appliances/clean-up.html
/appliances/cooking/appliances/cooking.html
/appliances/cooking/appliances/dishwashers.html
/appliances/cooking/appliances/package-deals.html
/appliances/cooking/appliances/refrigeration.html
/appliances/cooking/appliances/warranties.html
/appliances/cooking/appliances/water-systems.html

This is only one example. There are thousands of these URLs and many categories are affected. The URLs that 404 are not in the category tree and GSC does not show them linked from any page.

I apologize if I'm not providing enough information. I've never seen this before so I'm at a loss. Thanks in advance for any help.

[Tom Robertshaw]

Do you have any extensions or cutomisations that affect the filtering system on categories. If there definitely aren't subcategories that much these, then it could be that a filtering extension is trying to create "pretty URLs" for some filters/attributes. 

Can you double check your sitemap and do a test crawl of the site using something like https://www.screamingfrog.co.uk/seo-spider/ to see if you can find anything that links to these URLs. If not, it should be safe to request removal of those URLs in GSC.