I am experiencing the same issue. Video players on iOS used to fail to load videos but now they do not play sound. I am also a VRC subscriber, as I really want to support the platform, this is further prompting me to cancel my subscription. Several people are having difficulty loading videos on PCVR and VRC-Support stated that this is not their issue but rather a problem with YouTube. They have offered no assistance. I have explained that I am being forced to pay for a VPN to get the videos running, even though my service provider states that it does not block YouTube or VRCchat. It’s a shame when you really need support they offer close to nothing but quite happy to take your money for the subscription.

Eight months later, this issue still exists on AVPro-based players on iOS.

This is known issue so technically dupe report