Graphite Google acknowledges the fact that under some conditions it's better for the battery to limit SoC to 80%.
(If we exclude all other lithium variants than the old Li-ion like NMC, aka not LFP, LiS, LTO, etc:)
This is what they say about car Lithium batteries aswell. Prefer max 80%, but at least keep below 90%. Same at the bottom of the battery.
Then there are certain battery chemistries and packaging combination that only lose 10-15% capacity over 300 000 km with mainly fast charging, and some taxies with over double range and barely any more capacity loss . That is A LOT of
charging cycles. We are waaaaaaaay past the 1000 or so for phone batteries.
Now that the more high performing chemistries are being used in prismatic/pouch packaging aswell, not just cylindrical, we'll start get some hints if that type of packaging is to blame for capacity and lifetime loss. Pouch used to be a shortcut to death. Let's see what kind of improvements they have done, and if any of them have been translated to phone batteries. I suspect not, couse dead battery most of the times mean purchase new phone. And properly packaged pouches need to be put in a high pressure cages to restrict bloating that every charging cycle creates. Have anyone ever seen any of those when disassembling phones?
Phone batteries can be as good as they want, but they are designed to die within 2-3 years, just because it benefits the manufacturers. If you want something changed, pressure goventment agencies to create new rules and restrictions for phone batteries, couse as I said: replacing the phone every 2-3 years benefits the manufacturers.
Until then use the old and known tricks to extend the lifetime of the crappy made batteries. These tricks have never changed. Some chemistries+packaging combos just became so good it became less of a problem. If only they started improving phone batteries the same ways...