Well, the share link returns HTML that requires JavaScript. So if FB tries to “unfurl” (e.g. click the link, to summarize content for a message stream), the BTH link is only a redirect to the App Store with no HTML body - and FB may not like a link that leaves the app or needs JavaScript to render…
Whatever app you select for use with BTH share, when receiver clicks the link… that BTH link needs to run in a real browser, so that query parameters are provided to the BTH home app (i.e. market:// or http://app.apple.com/… which means navigate to an APP) on the shared user’s phone. So if shared by email or SMS, then the URL is likely to go through without modification, and email or SMS will send http:// to a browser. So yeah FB processing URL, and blocking stuff to keep you in their ecosystem isn’t surprising ;).
<html>
<head>
</head>
<body>
<script type="text/javascript">
var userAgent = navigator.userAgent || navigator.vendor || window.opera;
if (/android/i.test(userAgent)) {
window.location.replace("market://details?id=com.mikrotik.android.freevpn");
}
else if (/iPad|iPhone|iPod/.test(userAgent) && !window.MSStream) {
window.location.replace("https://apps.apple.com/us/app/mikrotik/id6450679198");
}
else {
window.location.replace("https://mt.lv/bth");
}
</script>
</body>
</html>