Ah, I misread that the first time. This looks like a bug in JFBConnect. I was able to reproduce the issue on my site with a secondary language. The way we're building up the menu item link is not sufficient anymore without adding in the language. Previously just supplying an ItemId was enough for Joomla to route it to the correct language. This has probably been a bug for awhile on J4.
I have a couple lines of code to change. The following are the code changes. If you don't want to perform the changes yourself but would still like to test it out before a release, you can use the Contact Us form to send FTP credentials.
Code changes:
In /components/com_jfbconnect/libraries/utilities.php
line 192 change
$link = JFBConnectUtilities::getLinkWithItemId($item->link, $aliasedId);
to
$link = JFBConnectUtilities::getLinkWithItemId($item->link, $aliasedId, $item->language);
line 200, change
$link = JFBConnectUtilities::getLinkWithItemId($item->link, $itemId);
to
$link = JFBConnectUtilities::getLinkWithItemId($item->link, $itemId, $item->language);
line 210, change
static function getLinkWithItemId($link, $itemId)
to
static function getLinkWithItemId($link, $itemId, $language)
after line 221, add
if($language != '*')
$url .= '&lang=' . $language;
-Melissa