What it catches
Links from young accounts. Banned domains. A keyword the mods are tired of, including 'I built' and 'check out' in some subs. All-caps titles. A comment that is only a URL.
You usually get a removal message that says the bot did it, sometimes with the rule name. If there is no message and the logged-out profile is empty, you are looking at a shadowban instead. Do not try to beat AutoMod by rewording the same link five times. That is the pattern it was configured to catch. Read the rule, wait, and comment without the link until the account clears the number printed in the sidebar. Each sub configures this alone.