I have a map that is displaying on all other environments except on production, I get the following errors:
I am using version 4.14 <script src="https://js.arcgis.com/4.14/"></script> for scripting. What may be the cause of this issue?
The error is pretty specific that it "failed to load the portal item". Since I can't see any of your code it's hard to suggest anything, but since it opens in all environments except for production, my guess is that you have been working with a map that's only shared to a local user, and you need something outside of the firewall. There could be other reasons why a Map wouldn't show but you don't present much to work on.
If you are trying to present a map outside of your firewall then you should check the URL of the REST endpoint separately to make sure it works. If it does, then there's something else going on.
It also might be good to look at the network traffic and see what the failed request looks like (e.g. 403 error, 404 error). Also, if you could post a simplified repro case on something like codepen, that would help diagnose.