Why is the email formatted wrong?

In my Laravel 9 system for pistol competition when creating a competition an email is being sent to be able to link to the competition itself.

But the link address is not created the right way.

This is the statement (in notification-html.blade.php):

{{ url($notification->link) }}

and it creates this link:

http://shoot.mywire.org/${http://shoot.mywire.org}/app/competitions/39

which does not work of course. It should look like this:

http://shoot.mywire.org/app/competitions/39

It works fine in earlier system on Laravel 5.3

What’s wrong with the statement?