When the participant (any role) pastes a long URL in the chat box and hits "send", the URL shared is not complete.
If the character limit is exceeded when copying a text in the chat box, the extra characters (ending) won't be sent.
There is a limitation to the number of characters that can be sent in a single message in the chat, applicable to any participant (300 characters limit).
Related article: Chats: general vs private
If you need to share via mashme chat a URL that exceeds this limit, you can use a URL shortener to make it more user-friendly and easy to remember.
Here you can find some Chrome extensions for it: Chrome Web Store - extensions for "URL shortener"