Don’t forget the post you are referring to was before this update and as I said quite the opposite.
In this case, at the moment it’s working fine in that although the sensor may read zero the auto brightness does not drop to zero but at some time, maybe in the morning there is plenty of light but the sensor reads zero. So unless the phone is turned towards incident light it record no light
Hey thank you for the proposed solution. I will test this now.
Could you maybe edit your original post because the forum did not show your reply with the solution untill I clicked the ‘2 replies’ button. If you edit your original post, people will see the solution faster.
Edit: Tried it, but no cigar. Turned adaptive off for now…
Hi @Ciaran and welcome to the forum.
The post you refer to is not a solution but I have found many adjustments make a temporary change.
It will be good to hear from you what happens when you try the ‘advice’. Please keep this topic updated with your findings.
Thanks
I know, but as I have already pointed out, the change in the latest update obviously made the issue worse, so more users likely will experience it.
We shall not forget that the OS is learning all the time, and these sudden backlight changes might have produced a lot of weird patterns which - theoretically - cannot be applied by the backlight controller…
Terrible behavior! The Auto brightness feature is totally unusable this way. Why are things messed up with updates? I hate buying problems with others being solved. Can I downgrade?
Hi Yes you can downgrade but it’s not automatic, you have to install an older version manually.
The downloads are available via
Ok the good news is that this morning the auto brightness seems fine.
I can cover the ambient light sensor and the screen is very usable, darkish as I would expect but would be good for the night.
Maybe the phone does have a brain or it just mine getting to see the light.
OK
I am interested in what your phone does after a restart … Are the set values saved?
I haven’t restarted my phone for days, since I wanted to mess with formatting SD cards and had to remove the battery.
As things seem to be improving I’ll see if in another few days all has stabilised and then I’ll do a restart and update here.
I think sometimes it’s better to face the truth…
cu
The problem with the truth is that it is relative to the enquirer. It is true for some that it is now daytime, for some it is night, for some twilight and for someone off planet they can see that each is true and false and not something they can decide or experience and hence know.
OK There is an official response to the issue that it is being looked into.
I have started getting this in daylight and artificial light. Most annoying. I will try turning it off and see what happens.
Turning off the Auto brightness does avoid the problem, but is is being officially looked at.
However after 5 days mine has been stable for since yesterday evening. So hopefully there is some algorithm that I have managed to force into a useable function.
I should wary of speaking too soon, roll on the evening when the light dims.
I don’t know what that’s supposed to do?
I’m waiting for a official fix …
unfortunately that doesn’t fix the problem for me. 
Steven
Nice! 
Then we have to wait and see first.
Steven
Maybe solved in LineageOS 18.1, but it is just a guess:
https://review.lineageos.org/c/LineageOS/android_frameworks_base/+/309848/
Hi,
I have the same issue, and I only have it since the last update.
All workarounds I read here, are working for a day at the most on my Fairphone. The next day it re-appears at some moment. Especially, switching auto brightness off doesn’t help because my phone now adjusts its brightness even when I switch auto brightness off.
It’s annoying because it prefers to happen in dark on the go when I quickly want to look something up or call someone. Having to go to the settings and to find the brightness slider in the dark in order to see something at all, is a bummer.
I really hope they roll back this “improvement” as soon as possible.
The brightness is two fold.
The sensor takes a reading of the incident or refracted light and this is used by the Auto Brightness algorithm to decide how bright the screen should be.
There seems to be a problem with the interaction.
a) The ambient light sensor has been reading
b) The Auto brightness setting is over-riden somehow