Why Huawei devices cannot play WebRTC video from Ant Media Server?

Yeah this problems happens in devices such as Huawei p20 and p30 pro. Because they don't support H.264 support in their WebRTC stack.

So enable VP8 in Ant Media Server. According to your case, maybe enabling VP8 and disabling H264 may resolve all your problems. On the other hand, If you need to have better level of compatibility you can enable H.264 and VP8 and also add adaptive bitrate that makes the videos transcoded into the other codec as well.