Google will penalize your website if you did something that Google does not like.

Google says that you should avoid automatically generated content. You should not participate in link schemes, you shouldn't create pages with little or no original content. Do not cloak your web pages and avoid sneaky redirects, hidden text or links, doorway pages and scraped content.

It's also not good if your website consists of affiliate links without without adding sufficient value. You also shouldn't load your web pages with irrelevant keywords and you should not use rich snippet markup that is not related to the page. Of course, creating pages with malicious behavior, such as phishing or installing viruses, trojans, or other badware can also lead to a penalty.

Before you start, you have to find out if Google really penalized your website. A penalty is a manual action from Google. Log in to Google Search Console to find out if your website has been penalized. If there isn't a message in GSC, your website hasn't been penalized.

If you see a massive ranking drop although your website hasn't been penalized, your website might have been hit by a ranking filter. Google's ranking algorithm contains sub-algorithms such as the Panda algorithm. If Google finds that a website has a low quality, they downrank that website.

According to Google's search quality evaluator guidelines, websites should have expertise, authoritativeness and trust (EAT).

Google won't notify your if your website has been affected by a filter. You have to monitor your rankings to find out if your rankings have dropped or not. The Ranking Monitor in SEOprofiler marks dates with confirmed Google algorithm updates so that you can compare ranking changes with the update dates:

In this example, the rankings of the website were not affected by Google's last three updates. The competitor website might have been hit.

There are site-wide penalties that affect the entire website, and there are partial penalties that only apply to a section of a website. If you have received a manual penalty, the notification in your Google Search Console account will inform you about the reason for the penalty.

Usually, it's one of the following: Hacked site, user-generated spam, spammy freehosts, spammy structured markup, unnatural links to your site, thin content with little or no added value, cloaking and/or sneaky redirects, unnatural links from your site, pure spam, cloaked images, hidden text and/or keyword stuffing.

Further information about the different penalty types can be found here.

"Seeing changes in knowledge panels that I think happened recently. The left side submenus that used to be there for entities are now mobile-like pills."
 knows when this rolled out, but seeing it consistently now.

"I suspect this wouldn't be the first place they'd try to cut corners, so it seems like a red flag to me. It doesn't change rankings, users aren't dumb & notice it too, so why risk it? I can also offer a look of disappointment, if that's necessary."

"Should we be filtering sites / pages stronger like that which are just created for messing with / testing the algorithms? That's not something which needs to be indexed, and starting a thread without mentioning the artificial nature seems a bit misleading."

"Now, when you reach the bottom of a search results page on your phone, the next set of results will automatically load with relevant information. [...] In fact, most people who want additional information tend to browse up to four pages of search results. With this update, people can now seamlessly do this, browsing through many different results, before needing to click the 'See more' button."