Hello, wanted to chime in to say I'm experiencing an issue with this same behavior as well, though for different reasons.
We have a number of android devices deployed to our warehouse team and drivers; these devices are locked down and managed with MDM (Esper.io) so the devices can only run the necessary line-of-business apps (e.g. to prevent device users from installing random crap and/or using the work devices for watching videos, web browsing, etc).
The device deployments included 3CX. When the device is assigned to the user, they could simply log in to the web app, scan the QR code, then they were good to go. All required permissions are granted to the 3CX app by the MSM platform as a managed app.
However, since v20 now REQUIRES/FORCES the user to set the battery management setting in order to continue to use the 3CX app, we can no longer use the 3CX app since the devices are locked down thus do not allow users access to the Settings app.
Is there a way this setting can be bypassed for managed devices without access to the Settings app? I have inquired with the MDM provider, and there is no means of setting the Battery Restriction setting for the 3CX app via MDM.
In short, please either allow for the 3CX app to be used without changing the Battery Restriction setting or allow a way for this check to be disabled on managed devices (such as with managed configurations).
We won't be deploying warehouse/truck devices which are not locked down and managed, so if this challenge cannot be surmounted, then it may require re-evaluation of our VOIP phone system selection.
Edit: Managed devices for employees are Pixel 6a's running Android 14