It’s common for site migrations or search engine updates to accidentally...

https://stateofseo.com/should-i-301-redirect-old-urls-or-leave-a-404-the-reality-of-content-decay/

It’s common for site migrations or search engine updates to accidentally resurrect outdated, low-quality pages that you thought were long gone. If indexed archives are cluttering your site and hurting your rankings, it’s time to act