Participant cannot see another participant video

Hello everyone,
I’m just developing an app for my jitsi meet. why the participant cannot see another participant’s video? is it because lack of server resources? or device resources? and is it possible to show the camera to all participants?

the following is an example of a screenshot of the display I mean.

this problem often arises when conducting meetings using android. in the web version and the ios application sometimes only appears partially, but not as bad as when running it on the android application.

btw right now I’m using VPS with 4vCPU and 16 GB RAM with docker jitsi installer. I’m planning to do another test again on a bigger server. but before that, I want to make sure about this.