>>149645847
>problem solver
Absolute Solver. Short for The Solver Of The Absolute Fabric.

Cyn and The Absolute Solver were not always the same thing. At the beginning of Episode 5, we see the original drone (before being found by Tessa, dig out out of the dumps, and named Cyn because of the damaged Marked For Disassembly armband) waking up from death as a Zombie Drone. For a split second, you can see a message on the drone's visor from the Absolute Solver entity, manipulating the drone to let it inside. Which it does, under the deal with the devil promise of "I will not discard you".
The Solver, as Cyn, later repeats this to Tessa in the same episode. Which draws parallels to how The Solver took Cyn, and then took Tessa.
As others have said, how long it took for The Absolute Solver to fully replace Cyn is up for debate and down to headcanon.