I encountered a video playback error on my website. Interestingly, the video loads normally on Chrome and Safari on Mac or iPad, but it doesn't play properly on Safari for iPhone.

I noticed the problem a few days ago but prioritized developing the Emilia app, so I put debugging on the back burner until today. However, my source code hasn't changed at all. It was code that originally worked fine. But after analyzing the source code and the symptoms, it turns out that the video wasn't working due to changes in the Safari algorithm for iPhone after an Apple update.

This happens a lot in development. My system was working fine and there were no changes, but it malfunctions due to other external changes. This is true not only in development but also for people and society. We should not be complacent, always check to see if things are okay, analyze, and improve.