Syncthing-Android: the battery policy called 'optimized' used a LOT of battery

I have Syncthing 1.27.6 on Android 13. Hitherto I had had the Android battery policy of ‘unrestricted’ set for Syncthing. I changed the policy to ‘optimized’. The result seems to be that Syncthing used 17.6% of the battery since the last charge - which is much more (some 10% more) than previously.

Is this a bug? A known problem that should be in the release notes of synthing-for-android? A co-incidence? (I do not think though that I made Syncthing sync a lot of data during the period at issue.)

Except, ah: when I opened Syncthing just now, it prompted me to let it set battery settings. After I concurred, I looked back at Android’s battery page for Syncthing, and none of the presets - ‘Unrestricted’, ‘Optimized’, ‘Restricted’ - was selected. Is it then that Syncthing is prompting to set a custom policy and works best with a custom policy? IF so, then I think the user should be told that - and told, as part of that, that the policy will show, in confusing fashion, as a kind of none-of-the-above within Android’s settings.

There has been no significant changes in the Android app for at least a few months. When it comes to technicalities, the “unrestricted” policy means that the app is allowed to run all the time, including during doze mode. When set to “optimised”, the app is suspended when Android enters doze mode. This should be the only difference between the two as far as I’m aware.

tomaz: so, Syncthing does not set some sort of custom power policy? If it does not, how to explain my observations?