Ok, there are multiple redirects involved!:
curl -Ii http://up2school.com/.well-known/acme-challenge/Test_File-1234
HTTP/1.1 301 Moved Permanently
Location: https://up2school.com/.well-known/acme-challenge/Test_File-1234
curl -Ii https://up2school.com/.well-known/acme-challenge/Test_File-1234
HTTP/2 307
location: https://up2school.com/fr/.well-known/acme-challenge/Test_File-1234
The first one works.
The second one breaks the challenge request path.
But that second one happens in the HTTPS vhost.
Can we see that config?