There are a lot of gears at play to make this site display properly.
The site itself is on a host (CloudFlare) which also goes down from time to time and nobody can see the site but we see a CloudFlare error. This is the first part.
Then the software itself (XenForo) assuming it's the latest version, should not have any issues with the BB Code tag because the tag is simply displaying an image on another site. This is most obvious in this thread here:
https://christianchat.com/christian-family-forum/can-you-guys-post-something-funny-please.179823/ where people are hotlinking images from other sites.
So, what you see in this case is that the page of the forum loads right away, but the image could load slower than the site.
And that's how it's supposed to work because the load time or PING time to the site CC Chat and the image that is BB Tagged are in two different geographic locations, the servers are, with different PING response time.
Another way to test this is if you have two devices, they could be two laptops or two phone or one phone and a laptop.
Install a VPN software on one of them.
Then go to that link i posted above and browse the pages. One with the VPN on and one without the VPN on.
You will see that some images don't load, but on the device without the VPN running, they will load.
The other caveat here is that some sites which store pictures for sharing, only block VPN ip addresses which are known. But Facebook does a better job with their algorithms to block hotlinking to a wider segment of the internet.
Google for example has criticized them for being "Walled Gardens". That's ironic coming from Google by the way but that's not the point. The point is algorithm.
So there are a lot of parts moving to make the page load and display properly which is why we experience these issues with display.
Then to add another wrench into the mix, it seems that the Chromium browsers have gotten an update on September 19 which is affecting javascript commands, specifically emoji reactions on this site.