URL leading characters issue

[Shellback2348]

When I select a story on a google email from Haystack using Firefox or LibreWolf browser there are leading characters ahead of the normal URL. If I remove that part (which I made bold in the example) the story run as expected.

Here's an Example: https://notifications.haystack.tv/CL0/https://www.haystack.tv/v/private-island-river-nile-ultimate-luxury-ugandan-retreat

Any idea what is adding the leading characters and causing FF not to run the story. Not noticing this in any other application.

FYI, sent a note to Haystack; still waiting for a response.