Disconnecting on Android

Hi everyone, i am wondering if anyone can help us out. Me and my friend are using discord for private calls for years now. For few months now her calls just randomly hang out(literally ends the call for her, not just disconnect and wait for reconnect) by themselves. It's not afk disconnect, we are both on call when it happens. It's private call so there is no afk limit and it even happens in middle of sentence. Sometime it doesn't happen for day, sometime it happens 3 times in 10 minutes. She turned off her battery saving and gave discord all the permissions imaginable to use battery however it pleases. It's happening on android, xiaomi redmi note 9 pro, miui 12. Anyone having same issue or possibly anyone who fixed this issue? I should mention that it's mostly (not sure if exclusively) happening when discord is out of focus, but it's hard to imagine anyone who's on call just stares at the screen with the call all the time.