Why do Twitter, Slack, and some other apps not correctly parse full links that end in period(s), tilda(s), etc?

If you paste a link such as https://stackoverflow.com/questions/ask. into a Tweet, Twitter will convert the text into a link. However, it will parse only the link before the trailing punctuation, so the trailing . will not be part of the link.

I understand these apps are probably using some common "linkify" script to auto detect and parse links, I'm just curious what that library is and what the specs are, so that we might add some tests to our app so that deep links will always be easy to copy/paste without problems into these social apps.