Curator_cli: filter suffix pattern seems to be acting like a regex pattern

Hello,

I'm using curator_cli version 5.7.5.
When the following command was executed, the filter pattern matched every single index (and consequently deleted every index). Is this expected behavior? From what I can tell in the documentation, it seems like a suffix match should be a substring match, NOT a regex match.

$ curator_cli delete_indices --ignore_empty_list --filter_list '{"filtertype":"pattern","kind":"suffix","value":"/?"}'

Thank you for your time and consideration.

 - Daniel