When I watch video submissions from the web on my phone, there is no sound.

Since the last(?) Since the system update of the last time(?), when I browse seaart's submitted videos from the web on my phone, I don't hear any sound at all. The videos on the works page have sound, but the videos of submitted works have no sound at all. Is it just me, or does the sound come out on the smartphone app and PC web, but not on the smartphone web?