Deprecation warnings when making thank-you letters
In 5.31 and master only:
In a recent commit you can no longer pass attributes to CRM_Core_Form::add() as a string. The PDF letters still do this though, so you get warnings like
User deprecated function: Attributes passed to CRM_Core_Form::add() are not an array. Array ( [civi.tag] => deprecated ) in CRM_Core_Error_Log->log() (line 58 of .../sites/all/modules/civicrm/CRM/Core/Error/Log.php).
Also, I understand why it's a warning, just since it swallows the backtrace you then need to edit the line in CRM_Core_Form to log a backtrace instead to find the actual problem (in case others are also seeing similar warnings now and trying to track it down).