It's Firefox that was redirecting the page: https://res.skyteam.com/Search/promoDefault.aspx?vendor=sky&promocode=5121S

to that one on the screenshot for the reason known only to it... lol... It works on Brave, but with SHIELDS off (as cookie thing blocking the page from loading)... The same is happening on the mobile version of Brave, too...

All in all, it works, but not a happily done website for sure... (understandable, it's Windows 😃)

Now, let's search for free flights! 🤣