Here's another example [0]: "Hacker Conference HOPE Says U.S. Immigration Crackdown Caused Massive Crash in Ticket Sales". A quote: "“We are roughly 50 percent behind last year’s sales, based on being 3 months away from the event,” Greg Newby, one of HOPE’s organizers, told 404 Media in an email." No reason to think this conference is especially different from others like it.

[0] https://www.404media.co/hacker-conference-hope-says-fewer-pe... OR https://archive.is/QWmxO