YouTube on Safari Mac doesn't load

This is what I see on the YouTube page on Safari on Mac. This happens as soon as I get into my YouTube account. If I don't log in it's fine, if I log in with someone else's account it's fine.

I've tried all the solutions I've found on the Internet so far to no avail... Even if I use another profile on the Mac, but I log in in my YouTube account, I get the same result.

No issue on the iPad, no issue on the iPhone, just the iMac and the Macbook! So I think it's something related to the YouTube website. My iMac and Macbook have different MacOS, so it's not OS-related...

I've also sent a feedback to Google / YouTube.

Is anybody else experiencing the same thing? Any idea?

Thanks a lot