CORS problems on Quality assurance and testing course

I’m making this lesson, and I have the solution on glitch, I look at the solution and it is answered correctly.
But I still have the same error:
Request from another source blocked: the same source policy prevents reading the remote resource at (reason: CORS 'Access- hea![example|601x500, 75%](upload://3sEUJzrSBJd3DzLHlOsT9piJ4Ic.png) der is missing Control-Allow-Origin ').

and every time I submit I get different answers, maybe this is all wrong, or just one of the three or maybe two

I place this on the “tests-route”:

cors({origin: "*"})

and after some attempts it works (maybe luckily)