Safari and Google Sites compatibility issue

I run a website building service using Google Sites (digital wedding invitations), and I'm seeing the exact same compatibility problem described above, across multiple different sites built on the same template.

Example site: https://sites.google.com/view/4paocar/i

Issue:

• On some iPhones, the site fails to load correctly in Safari — it shows a blank/white screen, freezes, or fails to render part of the content.
• Clearing Safari's history and website data fixes it temporarily, but the issue can reappear later.
• The site works correctly on other devices and browsers (desktop Chrome/Firefox, Android).
• Safari Private Browsing also loads the site correctly and consistently.
• This happens across multiple different iPhones, not just one device.
• The issue occurs on multiple different sites built with the same setup, including pages with and without embedded audio, so it doesn't appear to be caused by any specific embedded element.
• The content and code of these sites haven't changed in years — this issue started appearing recently.
• Sites are public and don't use a custom domain.

This looks like the same Safari/Google Sites compatibility issue reported above, not something specific to a single site's content. Any update on this would be very helpful, since it's affecting real users (wedding guests trying to open invitations) and there's nothing on my end I can change to fix it.

Thank you.