A website is dealing with an increase in spam URLs linked to their domain in Google Search Console, leading to a doubling of the indexed URLs. They are considering adding rel=canonical tags and disavowing the spam URLs as possible solutions, but it is unclear how successful these measures will be.
Experts are advising website owners to check their Google Search Console for any pages associated with their domain that may be causing problems with duplicate content. They suggest ensuring that any invalid URLs serve a 404 header response, as returning a 200 could indicate a potential hack. If the pages are considered duplicate content by Google, experts advise against using the disavow tool.