The hostname (h2gallery.com) does NOT match the Common Name in the certificate (example.com). This certificate is currently invalid for this host.
What to do?
I tried deleting all the related files and no matter what I do I think the old cert for the domain is being served and where I might have entered "example.com" as my domain by mistake at some point.
Please fill out the fields below so we can help you better. Note: you must provide your domain name to get help. Domain names for issued certificates are all made public in Certificate Transparency logs (e.g. crt.sh | example.com), so withholding your domain name here does not increase secrecy, but only makes it harder for us to provide help.
Your site is indeed sporting a self-signed "example.com" certificate. How did you get your Let's Encrypt certificate(s)? I.e., which command did you use?
Also note that you've issued 4 IDENTICAL certificates already: crt.sh | h2gallery.com Usually, when there is an issue with the installation of the certificates, it's no use at all to keep issuing brand new, but unnecessary certificates.
Probably not (yet). It's probably a misconfiguration in your webserver stack, but in my opinion Bitnami is such a #)($#()_#())#@( piece of )#($)#($*() and I have absolutely zero knowledge of Bitnami (just looking at guides such as the one you've posted just makes my eyes hurt and makes me want to cry), so I believe I'm not the correct person to lead you through the process. But there are a lot of other people on this Community of which perhaps someone can help you instead of me. Just be patient