That might be the reason because, after much googling and experimenting and creating new Glitch projects to identify the error, I’ve found that when you add a link to glitch.com or a project page, the link works. But when it is linked to another webpage, you either get the error REQUESTS TO THE SERVER HAVE BEEN BLOCKED BY AN EXTENSION or DOMAIN.COM REFUSES TO CONNECT.
What I’m guessing is that the websites that are being linked to might be sending X-Frame-Options: SAMEORIGIN response header. This option prevents the browser from displaying iFrames that are not hosted on the same domain as the parent page. But I’m not completely sure…
From what I’ve read, try clearing the browser’s cache and open the project page in an incognito tab.
This might be helpful: https://stackoverflow.com/questions/8700636/how-to-show-google-com-in-an-iframe