Bluetooth not working properly on mid 2011 iMac

I'm having stability problems with my Bluetooth connection.
I use a 21 inches Mid 2011 iMac and I'm running the latest version of eOS.
The connection between my Magic Mouse and my Magic Keyboard is unstable; with no reason, they suddenly both disconnect, even though they result connected on Bluetooth Control Panel.
It happens sometimes when I don't use them for a long period (30 mins to hours) and in situations when I'm actively using them as well.

I have to say I had this problem with different previously installed distros (Ubuntu, Manjaro, etc.), but it's way worse on eOS.
I don't encounter this problem when running OS X.

Installed Kernel: 5.3.0-40-generic
Installed version of eOS: 5.1.2 Hera
Installed version of GTK: 3.22.30

Machine:
Quad Core Intel® Core™ i5-2400S CPU @ 2.50GHz
Advanced Micro Devices, Inc. [AMD/ATI] Whistler [Radeon HD 6630M/6650M/6750M/7670M/7690M]
Memoria: 4,0 GB
490,7 GB storage (HDD)