I'm not sure I follow who has an error where, but just to clarify, the version of fof/formatting will have no impact on this. You should however check whether you are running the latest version of the s9e/textformatter package, which is where the code was changed to allow x.com URLs.
I remember discussing this previously, maybe earlier in this thread, where we identified the specific version in which this was added.
When running a global composer update, TextFormatter should get updated. If you only manually update this specific extension, it might not update its dependencies unless you use the -W flag.
Don't forget to clear the forum cache after updating TextFormatter, otherwise you might have odd behavior where something works in the final post but not in the preview.
