True, all those messenger links are ghosts from the past. PHP 7.2 brought a couple of headaches for me with addressing an ever-expanding PHP Deprecated messages both in the error_log and the SMF errorlog. Looks like they used create_function() calls a lot, and that (along with each() ) is deprecated in PHP 7.2.
A quick change to php.ini to suppress deprecated errata and a change to Sources/Errors.php to not log E_DEPRECATED errata stemmed the flood of error messages clogging both logs.
Other than that hickup, the forum seems to be performing normally after the upgrade of PHP.