Also some people encounter battery drain problems since the upgrade to A13 (like myself, see FP4 battery life got worse after Android 13 update - #209 by Lars_Hennig ). Can you check the root cause for your battery drain?
Feeling you have been cheated is something nobody will be able to change, but together we could try to find out if the battery drain issues on the FP4 all have something in common or not.
No this battery drain started with the 5th of septemre, the security update.
Iām not willing to root this device again to troubleshoot. (or do some adb magic I do not understand)
Why do you think you have to root the phone? If you use the battery usage from settings you might see the mobile network in the top ranks of apps using up the power. That would at least give a hint leading to the same problem I described in my post.
Good morning,
A few days ago I posted a criticism of Fairphone, specifically about the battery management of the Model 4 and the lack of an Android update.
Last night I received the announcement of the Android 15 update and I installed it immediately.
I havenāt had any problems so far, and the battery drain has clearly returned to normal.
Just as I criticized Fairphone, now itās only right that I congratulate them on this update, which solved two problems in one fell swoop.
Thank you.
Moin,
Yesterday, I updated to Android 15. The first attempt ended up with a permanent reboot of the phone, but āswitching backā to A13 was surprisingly easy and quickly done. Before the next attempt, I changed from Nova-launcher to Quickstep and the update succeeded smoothly. Changing back to Nova then was as easy and everything seems to be working perfectly 
Besidesā¦ thereās no change about the energy consumption: itās still 3-4 % per hour at standby, as itās been after the last update in September. What a disappointment! 
Cheers,
Thomas
In my case of a Fairphone 4 which used to have an intolerantly fast battery drain even when idle, the latest update to Android 15 seem to have fixed the drain.
So I can now sell a replacement phone I had to get due to this issueā¦