Thanks again for suggesting possible issues.
I dropped in this post after checking out all possible reasons including the two mentioned.
our local browser hasn’t been able to pick up the new certificate and still thinking the site is using the old-expired certificate. The service provider might need time to update over its all CDN nodes.
Took care of cache and also tried in different machines, browsers under different modes. I doubt that this is the reason.
Hmm Are you using VPS or is there a firewall-like service in front of your Gogs instance (e.g. Cloudflare)?
I doubt that these are the issues as I had a fully functioning site as can be seen from the expired certificate still in place. For that matter, this system includes other live secure sites such as, https://aioradar.com, https://www.searchgiggle.com/spacegigglicious/ to name a few that are fully functional.
What surprises me is that the permanent redirect at the top is not working? If you have other ideas to make this redirect and SSL functional, please do share.