Google spam policies: did an update hit your site?

This is the thread for questions about Google spam policies.

Google lists every spam policy on one page, and a ranking drop after a spam update is not the same as a manual action. Check the Manual actions report in Search Console first.

I have answered the most asked questions on this topic here:
https://aiwebpageseo.com/spam-policies-answers.html

Which policy are you unsure about, or which update do you think affected you?

Reply below and I will answer.