Android on saving mode makes my keyboard jumps back to the standard keyboard?

When phone is on Ultra power saving mode, it jumps back to the standard keyboard:

This tends to incur in quite a few brands/models of the Android phone.
The Ultra Power Saving mode ensures that all processes that use extra memory (RAM) are stopped immediately. In such a case, it might happen that 3rd party keyboards such as Neurokeys are also affected by this and are therefore disabled.

There is solution for a few brands / models Android phone:

Samsung phones (for Nougat update):

- System settings > Battery (power supply) > Battery optimization > tap "not optimized" and select "all apps"> Search for Neurokeys > Select "Do not optimize"

Samsung phone (after Nougat update):

- System settings> Device maintenance> Battery> Non-monitored apps> Add apps> enable Neurokeys

Oppo smartphones:

- Security centre > Battery > Enable smart energy
-Saving mode> Energy
- Saving app management > Add apps> Check Neurokeys

Xiaomi smartphones:

- Go to the Security tab > Permission > Auto start management
- Add auto start apps > Check Neurokeys.