HTTPS Not Working - Invalid Certificate (MacOS)

Thank you for the additional info, @BrandynF. Our developers are aware of an issue with macOS Big Sur 11.1 and the creation of SSL certificates. For the time being, it’s safe to manually trust the certificates.

It’s also possible however that the error would appear in cases of mixed HTTPS and HTTP content on a page. Running a Search & Replace via plugin or the database may help catch those.