Hello everyone!
Vinted seems to be experiencing a general bug… which is affecting Clemz.
You have a blank page, with a URL that starts with « sessionrefresh(…) » sometimes Clemz flickers or doesn’t display at all.
Here’s how to fix it on any browser: clear your cookies.
For Yandex, here’s a tutorial 
Vider le cache dans Yandex Browser du cache et des cookies dans Yandex&text=Lancez l’application Yandex Browser,« Historique de recherche clair » .
For Chrome Vider le cache et supprimer les cookies - Ordinateur - Aide Compte Google
Regarding Kiwi browser, this browser has not been updated for several months, we advise you to switch to Yandex.
Are you using Chrome? In that case, it’s the same procedure as the tutorial above.