I reproduce the issue with
https://my.enalean.com/plugins/git/taas/tuleap-cloud/ansible
the fork modal generates the following link
https://my.enalean.com/plugins/git/TaaS/u/vaceletm/tuleap-cloud/ansible
while the correct URL is
https://my.enalean.com/plugins/git/taas/u/vaceletm/tuleap-cloud/ansible