Browser reports an HSTS Error. This only happens when visiting the URL via link, not when entered directly in the URL.
www.tcgcoda.netlify.app has a security policy called HTTP Strict Transport Security (HSTS), which means that Firefox can only connect to it securely. You can’t add an exception to visit this site.
The issue is most likely with the website, and there is nothing you can do to resolve it. You can notify the website’s administrator about the problem.
I’ve seen some posts on the forum about a similar issue being resolved by renewing SSL certificates, but I don’t have access to renew those certs on the starter tier.