I don't have a similar setup, but have noticed that I quickly reach the limit of the power the screen can deliver (at least I suspect that's what it is). I have my laptop connected via USB-C for transferring but also for charging, then a Bluetooth mouse and a keyboard. If I want to charge my mobile phone at the same time, that can already be too much. Then my mouse starts to lag, about every 20 seconds I have problems moving it smoothly. If I unplug the mobile phone, I no longer have these problems. But I have also experienced that I could charge my mobile phone without any problems while everything else was plugged in.

I'll have to see if I can regulate the laptop or the mobile phone so that they draw less (I don't know if that's possible). For now, I'll just charge the phone somehow else, even if the screen would be exactly practical for that with the many connections.