Update (November 8th, 2019): Juanito Fatas has pointed out to me this bug has now been fixed.
Safari 12.1.1 has a strange issue with certain ruby tags. Specifically, something like
<ruby>ホゲホゲ<rp>(</rp><rt>ホゲホゲ</rt><rp>)</rp></ruby>
which renders as
ホゲホゲ
If you control click on the above, and then click somewhere else on the page, Safari crashes with “This webpage was reloaded because a problem appeared.”
We use the ruby tag in Doorkeeper for showing the reading of event participant names, as in Japanese, it can be non-obvious how to read the kanji. However, due to this bug, it appears that clicking on event participants names now causes Safari to crash under certain circumstances, making it a more serious issue then it might first appear to be.
I tried reporting it via the only Safari feedback form I could find, but I doubt that it gets much attention, so I’d love it if someone knows a better way of reporting issues like this.