@nikballoon Hello, this issue might be related to the fact, that the company Let’s Encrypt has ended support for some certificates so some older browsers and older operating systems are experiencing these issues.
I can recommend using updated OS. Or if you still have issues, use the latest Mozilla browser 93.0., where you should not have any problems, since Mozilla downloads certificates on its own and does not rely on OS.
You can read more on this here – https://techcrunch.com/2021/09/21/lets-encrypt-root-expiry/