Many sites use certificates that are given out by trusted certificate authorities to protect against phishing. A certificate contains an open key used to encrypt data that the user sends to the site over an HTTPS connection. The certificate authority confirms that the open key used during encryption really does belong to the site owner.
Yandex.Browser checks site certificates. If there is any doubt about a certificate's authenticity, the browser will warn you.
You can decide to either not visit the site, or enter the certificate in your list of trusted ones. The certificate will remain in the list for 30 days, after which you will have to once again confirm its trustworthiness.
Antiviruses, ad blockers, site-monitoring programs, and similar special programs can substitute their own certificates for those of the website (in order to decrypt traffic). However, if special software is used to substitute a certificate, the following potential dangers can occur:
Decide if you are prepared to trust the certificate preparer with your personal information:
If the browser continues to warn you about a suspicious certificate even after disabling HTTPS checks, and you don't need the program that installed the certificate, try temporarily closing that program.