Old content never really dies; it just gets caught in search engine caches. If...

https://www.scribd.com/document/1016381165/Why-Do-Old-Content-Problems-Show-Up-at-the-Worst-Possible-Time-205018

Old content never really dies; it just gets caught in search engine caches. If outdated pages are suddenly resurfacing in your SERPs, you have a messy index problem