sudden crazy battery drain with SE 2020 can't be a hardware issue

Since getting my iphone SE 2020 two years ago I hardly ever let it drain to lower than 40% and always charged it overnight with Battery Optimization. i did ALL of the things that are recommended to extend the life.

then after an update around maybe 5-8 months ago, I wish i could remember what one, it began to drain insanely fast. Leaving it alone for 4 hours (with no apps running and bluetooth off) it was losing around 50% of battery! again NO APPS OR BT... straight to this from lasting all day with no issues to losing 50% charge in 4 hours from doing nuthin'..

So recently i decided to see what it did when on airplane mode and it the battery doesn't budge! I left it alone for 6.5hrs... still at 100%!!!

if it was a bad battery it wouldn't last like this. I feel like this is a frustrating mystery to SO many people that buy these phones. I think this is proof that it's a coding/software thing. and though i'm not accusing apple of purposely ruining phones (as everyone i talk to about it seems to believe) it is kinda crazy how this seems to happen to every model after a couple of years and with all 'geniuses' helping here the probs never go away once they start.

oh well. they got me... I went out and bought a 14pro because i couldn't stand the headache anymore. hoping i have a couple solid years before it starts drinking the charge like it was money.

I have the SE 2020 sitting here with AP mode off - went from 92% to 80% in the time it took me to do a little research on here and type this.