HUAWEI:

1) Battery Manager -> Power Plan -> SET to Performance

2) Battery Manager -> Protected Apps -> SET THIS app to protected

3) Battery -> Manage App Launch -> SET to manually

4) App pinning: 'lock' THIS app in the 'recent apps' view to prevent it from being killed by Android

Huawei Recent Apps Lock

5) see: https://dontkillmyapp.com/huawei