Recording screen on ipad with internal sound on Skype and Google meet

When I want to record my screen with internal sound after it finished, it doesn’t have any sound even my own microphone. I use it to record my classes but it doesn’t work, it doesn’t have my audio or the teacher’s or anybody’s on the class. It just record the screen without any sound and I don’t know how to fix. It appears on many apps like Google meet ,Skype or even Apple Music but it worked on some other apps like VLC . I don’t know how to fix it. I search it and I have nothing.