Huawei has its own unique take on Android that it calls EMUI. In addition to the regular Android battery optimization settings, there are some specific settings you can adjust on your kid's Huawei.
Adjust battery settings on your kid's Huawei
On your kid's Android, open the ⚙ Settings app.
Tap Battery.
Tap App launch.
Set Bark to "Manage manually" and make sure everything for Bark is turned on.
Then, open the ⚙ Settings app again.
Tap Advanced Settings.
Tap Battery Manager.
Set "Power plan" to Performance.
Under "Protected apps," add Bark to be protected.
Next, open the ⚙ Settings app again.
Tap Apps.
Tap Bark.
Tap Battery.
Uncheck Power-intensive prompt.
Checkmark Keep running after screen off.
Now, open the ⚙ Settings app again.
Tap Apps.
Tap Advanced.
Tap Ignore optimizations.
Tap the v dropdown menu at the top to select All Apps.
Find Bark on the list and set to Allow.
Huawei P9 Plus
If your kid has a Huawei P9 Plus, check these settings too:
On your kid's Huawei P9 Plus, open the ⚙ Settings app.
Tap Apps.
Tap Settings.
Tap Special access.
Tap Ignore battery optimization.
Select Allow for Bark.