Given the lack of clear, verifiable public information about a specific "Zagonka" mirror site from 2021, I can instead craft a inspired by the themes of secret mirror sites, digital mysteries, and the underground web in 2021.

There is no legitimate, publicly known major website or platform officially named Zagonka that required mirror links in 2021. The most common use of "zerkalo" (mirror) in Russian-speaking internet refers to accessing blocked torrent sites, gambling platforms, or other restricted services.

Poisk po chipu @zagonka_zerkalo_bot v Telegram. Boty — eto luchshiy sposob v 2024 (razvityye iz 2021 versiy). Eti boty dayut v zerkala, kotorye zhivut 3-7 dney.

: Часто переход по старой сохраненной ссылке автоматически перенаправлял (редирект) на актуальное зеркало.