Parse error: syntax error, unexpected '?' in modules/notify/notify.module on line 815 Drush command terminated abnormally due to an unrecoverable error

I just updated the notify module after months and am now receiving this whenever I run drush:

Parse error: syntax error, unexpected '?' in modules/notify/notify.module on line 815
Drush command terminated abnormally due to an unrecoverable error.                                           [error]
Error: syntax error, unexpected '?' in modules/notify/notify.module, line 815
The external command could not be executed due to an application error.                                      [error]

The line in question is:

), array('langcode' => $upl)) . ' ' . $shortlink ?? '' . "<br />";

I moved the notify directory out of /modules and reran 'drush cr' and it rebuilt cache just fine. I then ran 'drush dl notify' and 'drush en notify' (it was already enabled) and 'drush updb' to get a clean version of the code. The error returned with the updb.

I've had to disable notify again as I can't use drush with it.

I'm surprised not to find anyone else with this issue, so I'm wondering what I can do to help troubleshoot it.