iPhone 6s Battery issue

I've owned that device since it was new - it hasn't received a battery replacement.

What do you mean by 500 Cycles or 80% Health ? 500 recharges ... ie. about 2 years ?

I'm asking because of the sudden change in battery status after the recent iOS 14 I applied. Is there a way I can rollback to an earlier version ? Or perhaps consider a Jailbreak option - if that would help ?

Certainly the information upon the 69 US$ replacement fee for the new battery is helpful. (Though apparently I will only have a 20 US$ trade-in value for my iPhone 6s with 12GB ram)....

However, my question is, why, following the iOS 14 upgrade, has this issue suddenly arisen ? And isn't 87% considered good performance /capacity ?

Why when it hits 50% capacity does it drop off a cliff -edge ?

Should I/can I paste a picture of what I am seeing ?

I leave my iPhone with no other apps running over 24hrs and the same situation happens.... consistently... the Home Screen is seen as being the biggest Consumer of power.

OK, I think there are other processes running under iOS x.yz that we are not in control of, and it's these processes that consume the power and that we have no control of between successive updates... or information upon.

That maybe so, however I do not recall having had to replace the battery of my iPhone 6S.

But, regardless, we appear to be digressing from the 50% to 1% instant declined issue following the iOS 14 upgrade.

And, since the Update.. I see my battery at 1% regularly the next day.

We can say that it may, have nothing to do with the update, but still... I would like to understand how a battery can discharge 50% of its capacity immediately ?

The same IOS Update on my iPhone XR has noticable increased the surface temperature of my iPhone!

I had to remove it from my suit pocket for concern it may burst into flames! So powered it off...

So yes, I am concerned that there may be a correlation between the two updates. Heat = power usage.

With COVID, I don't normally wear a suit jacket, but today was an exception, and with my iPhone XR slipped into my Jacket pocket, it became a noticeable source of heat - the screen had become hot, and uncomfortable to touch, even though no apps were running.

I powered it off.

The ambient temperature wasn't that hot - maybe 24'C indoors, so I don't think that was a contribution.

However I feel something is not right, yet I do not have the tools available to pinpoint where the issue is...

Now, this is diverging a bit from the iPhone 6s issue - though the two issues are aligned... in both cases I have no way of seeing what is running under iOS in order to cause the high Power Drain.

Is there a debug mode, which I can invoke inorder to investigate further ?

FYI I use my iPhone 6s mainly as a WiFi - Home only device.