Safari - for better or worse - is setting the standard for many privacy updates, especially around 3rd party cookies and tracking.

Those updates broke a lot of websites - you might have noticed SSO failing, iframes failing, or websites confusing unmodified Safari users for adblock users.

Firefox adopted the changes a bit later. By the time they made the switch, I think most had resolved their sites because of Safari. Last I read, Chrome is slated to implement similar for 2022.

Not intended to be a defense of Safari, especially for OP's bug. But at least some breaking changes were deliberate and in the name of privacy enhancements.