Severe Battery Drain Issue After One UI 8 Update

[PARIJATRIKO]

I’ve been experiencing a huge battery drain issue after the recent One UI 8 update, especially during screen-off time. I’ve been using this phone for the last four months, and I had already followed all the recommended battery optimization steps suggested by Samsung in various posts.

It’s really disappointing to face such an issue on a flagship device, especially when my previous Galaxy M31s never showed this kind of problem.
Kindly look into this matter at the earliest.
(Screenshot attached)

[cs_member10]

Dear Samsung Member,

Greetings from Samsung Customer Support!

As per your concern, you have already done the possible troubleshooting steps and the issue remains unresolved, we kindly request you to share the log file. Also, share the video clips and images for better understanding. This will help us to investigate further and resolve the issues.

To share the log file: Open Samsung Members Application > Support> Tap on send feedback> Choose Composer> Select error report> Select the appropriate issue category> Type your query and send.

Note: To ensure relevant log information is included in the error report, submit the report within 3 minutes of encountering the bug or error, and do not terminate (swipe away) the Samsung Members application until you are notified that the report has been sent. This can take up to 5 minutes.

Warm Regards,
Samsung Customer Support

[NJ1978]

Exactly the same here. Had a perfectly working S21FE in amazing condition. Loads of storage great battery etc. . Oneui 8 downloaded & ruined my phone.  Samsung are completely in denial that this rollout caused this. Froze,  boot looped glitched , pixelated & kept crashing. Expert phone shop replaced battery & screen.  I was out of warranty with provider/ Samsung & their chat service was useless!  Worked OK for a day then happened repeatedly! Samsung are now saying they've " demoted" the One ui 8 update for S21FE until late Oct. Probably because the earlier one Fd people's devices up.   Need to admit that the first update wasn't ready & if you read other reddit/ samsung forums - a lot have the same issue. I will never buy ANYTHING from Samsung again . Phone had to be downgraded back to One ui 7 & still does all of the above daily.  Caused so much hassle & inconvenience!

https://www.forbes.com/sites/zakdoffman/2025/10/14/samsung-stops-updates-for-millions-of-galaxy-phon...