There are a few known issues with Optimized Frame Pacing.
We have some reports of issues on older devices here ( Optimized Frame Pacing - Freezes/Crashing on Android 6.0 and earlier ) but right now no bug report or a way to reproduce the issues.
There are also known issues with Optimized Frame Pacing on devices with variable refresh rate.
In Unity 2019.4 I would recommend to disable Optimized Frame Pacing.
Would it be helpful to turn the feature on/off during startup with the mechanism described here? Unity - Manual: Extend the default Unity activity. At the moment we don’t have a “command line” switch, but this could be added. It would be much simpler and probably more robust than allowing to switch it at runtime.