Snap CEO Evan Spiegel rarely appears in public or gives interviews. But in recent months, he could be found on Reddit, responding to complaints from Snapchat users about persistent problems with the Android version of the app.

In one exchange last fall, Mr. Spiegel promised “[s]ignificant Android performance improvements coming early next week, more to follow through the end of the year :)” In another post in January, after a user complained that the app was still buggy, Mr. Spiegel apologized: “Yikes. I'm sorry to hear that. What device are you on and which OS? We will take a look.”