Thanks @oseibonsu.
On March 9th, 2020, GitHub has banned my account without any notice for an unknown reason.
I found out about that only when people started sending me emails telling me that my hosted libraries have stopped working and asking me why did I delete my GitHub account (which I didn't).
Apparently, for any person other than me, when navigating to any of my libraries' page, GitHub simply displayed a "404 Not found" page. Not even a "user account suspended" page — nothing. Just as if the person didn't exist, and all their libraries too. GitHub, if you're banning someone then at least have some balls to publicly admit it.
The ban resulted in at least tens of thousands of people using my libraries not being able to access the source codes, not being able to report bugs or seek assistance when they're stuck. Some of my libraries also relied on "GitHub Pages" for hosting "static" assets (for example, country flag icons), and those have stopped working properly as a result.
The only hint from GitHub was when I navigated to their website and (only for me) it showed a notification at the top saying: "Your account has been flagged. Because of that, your profile is hidden from the public. If you believe this is a mistake, contact support to have your account status reviewed". I've sent a support request to GitHub, Inc. as soon as I found out about the issue (Ticket ID: 594578).What could possibly be the reason of the ban? Maybe one of my repos contained a mysterious "blacklisted" word? Or maybe I've accidentally called someone a moron on the internet (happens to anyone)? Does it really justify silently wiping a bunch of useful open-source projects hundreds of thousands of people rely on in production?
This incident should teach us all that corporations are still corporations, even when proclaimed the heart of open source, even when they've played a huge role in growing the open source community to its current state.The main focus of every corporation are good "public relations" image and silky-smooth operation. This giant machine can be your best friend as long as you don't stand in its way and are good for its business. But if you happen to get in the way, it can simply screw you over and won't even notice.

References:

* [The Schism at the Heart of the Open-Source Movement](https://www.theatlantic.com/technology/archive/2020/01/ice-c...)

* [Why use GitGud.io?](https://twitter.com/GitGudGG/status/1004164620230144001)

* [Github Nukes Repository Over Use Of The Word 'Retard'](https://www.techdirt.com/articles/20150802/20330431831/githu...)
* [Which GitHub alternatives/VCS service providers should you use if you value your right to free speech? Some disrecommendations and recommendations.](https://www.reddit.com/r/MozillaInAction/comments/3ihuqf/whi...)

* (caution: some people may find the following article offensive, but I've included it to preserve the "diversity" of opinions) [GitHub Hires Notorious Social Justice Warrior to Work on ‘Anti-Harassment’](https://www.breitbart.com/tech/2016/02/25/github-hires-notor...). [@CoralineAda: "Transphobic maintainer should be removed from project"](https://github.com/opal/opal/issues/941).
* [GitHub blocks developers in Iran, Syria and Crimea for political reasons](https://techcrunch.com/2019/07/29/github-ban-sanctioned-coun...).

* [GitHub "shadowbans" GoodbyeDPI repo](https://habr.com/ru/post/447902/) (in Russian).