iOS remote video freezes when using webrtc RTCMTLVideoView

Question

I made a very simple app using google webrtc using cocoapod (version 1.1.31999). The signaling and the tracks are fine. I'm testing on iPhone 11 and the remote video just randomly freezes for 5-10 seconds then unfreezes. Looks like some threading issue. Not quite sure how to debug this type of bugs.

I tried logging

func renderFrame(_ frame: RTCVideoFrame?) {
}

and when the video is frozen the method is not called at all. Then it starts firing again and video unfreezes. Could it be that multiple calls of currentVideoTrack?.remove()/add() causes issues somehow? Any thoughts are appreciated.

class RTCVideoView: UIView {
    private var currentVideoTrack: RTCVideoTrack?
    
    var rtcVideoView: RTCMTLVideoView = {
        let rtcVideoView = RTCMTLVideoView()
        rtcVideoView.translatesAutoresizingMaskIntoConstraints = false
        return rtcVideoView
    }()

    override init(frame: CGRect) {
        super.init(frame: frame)
        
        addSubview(rtcVideoView)
        // Add constraints for the rtcVideoView
    }
    

   ...

   func update(with videoTrack: RTCVideoTrack?) {
       currentVideoTrack?.remove(rtcVideoView)
       currentVideoTrack = videoTrack    
       rtcVideoView.contentMode = .scaleAspectFit
       videoTrack?.add(rtcVideoView)
   }
}