Ask HN: What can possibly trigger an idling phone to start playing music?

A locked phone is laying on the table and suddenly, without any interaction with it, starts playing music through YouTube music app. It's kind of not a big deal but as an engineer, I'm very curious to know what could have possibly triggered such a buggy behavior. Also, can this "something" be used as a security hole?

More context: the phone is on wifi, no Bluetooth devices are paired