maps.apple.com show 'Your current browser is not supported' in Firefox on Windows 11

For the last few weeks I have been using maps.apple.com with Firefox on Windows 11 without any problems. But today, 10 June 2025, maps.apple.com starts loading with Firefox 139.0.1, but then, after appr. one second redirects to maps.apple.com/unsupported and shows "Your current browser is not supported".

I haven't changed anything in my configuration.

What happened with maps.apple.com?

What should I change in order to make maps.apple.com working again?

[Re-Titled by Moderator]

Original Title: maps.apple.com @ Firefox