Ho provato quel sito web e non è successo nulla. Concesso che fosse su Firefox e Mac High Sierra.
Posso suggerire che nel tuo caso di solito la pulizia della cronologia di Safari risolva il problema.
Ecco cosa Apple dice come farlo.
Delete history, cache, and cookies
Here's how to clear information from your device:
To clear your history and cookies, go to Settings > Safari, and tap Clear History and Website Data. Clearing your history, cookies,
and browsing data from Safari won't change your AutoFill information.
To clear your cookies and keep your history, go to Settings > Safari > Advanced > Website Data, then tap Remove All Website Data.
To visit sites without leaving a history, turn private browsing on or off.
When there's no history or website data to clear, the setting turns
gray. The setting might also be gray if you have web content
restrictions set up under Content & Privacy Restrictions in Screen
Time.