Hello everyone.
My exynos S21 Fe(exynos) has idle battery drain issue when connected wifi. I investigated a bit and found out that phone does not go cpu deep sleep mode when when connected to wifi. Also, this issue persist when connected to wifi once. Only workaround i found restarting phone and not connect wifi even once. Unfortunately phone is not usable without idle drain. I tested idle night drain after restart and only mobile data and phone lost 3-4 percent for 7 hours and it is actually pretty decent for 2 year old phone. I got this unit second hand and don't know previous firmware version has this problem. I tried factory reset, csc change even flashing another region firmware but no avail. This is my xda thread link: https://xdaforums.com/t/sm-g990e-exynos-has-screen-off-deep-sleep-issue-after-wifi-connection-persis...
I shared some screenshots from bbs and gsam tracking programs. Anyone can confirm this behavior? Maybe i have defective unit.
TLDR; Probably exynos variants has idle drain when connected to wifi(persist after disconnection) due to firmware.
