SUMMARY
I am sorry if I put wrong versions and platforms.

I am on Pop_OS 20.04, I am using the gnome integration of kde connect (gsconnect), and after I put my devices (oneplus 8 pro, Huawei mediapad m5 pro) in sleep mode, the storage was disconnected after a bit of time. Every other command (even sending messages) could be issued, but I couldn't send files to my phone. But I could send files to my pc from my phone.

I then insalled KDE connect from the Pop store, and with this one, after I put my device (tested only on oneplus 8 pro, but I think it would have also happened on huawei), the device just disconnected and won't reconnect, I couldn't issue any command or move files)(didn't try to reboot, but it's not a solution).
I'm not sure of the version, but on the Pop store, it says 1.4. For GSconnect I am using the latest version
On android I am using latest version avalable on the play store (1.14.2).

On both devices, the app was set to not be optimised by the operating system.
My oneplus 8 pro is on android 10, and my huawei device is on android 9 (emui 9.1).

I only tested on Pop os (gnome), didn't try others.
STEPS TO REPRODUCE
1. Have a device on which it could happen 
2. Connect the device with GSconnect ot KDEconnect on gnome desktop
3. Put (or let them go) in sleep mode and wait some minutes

OBSERVED RESULT
The device has been disconected, and won't reconnect (or at least for a time). 

EXPECTED RESULT
The divice and storage is still accessible, and commands can be issued. 

SOFTWARE/OS VERSIONS
Linux: Pop!_Os 20.04 LTS  
(available in About System)
Gnome version : 3.36.2
Qt Version: 

ADDITIONAL INFORMATION