GrapheneOS
This is a really awesome feature that has some usecases besides allowing the battery to last more cycles. My Phone is on my desk at home where I work for most of every day. I'd love to be able to keep it in a cheap cradle at 80%. I've seen many phones in the mobile device park of our company bloat over time because they were kept at 100%. Keeping the Battery at a lower voltage should reduce the risk of them bloating a lot. Same goes for devices used as for example mobile access points or as test devices.
Ultimately, getting the Battery replaced in my phone is at the very least annoying, since they are glued in so I can't just order a new one and change it quickly. I'd rather have the lower capacity and carry a cheap powerbank in my backpack if that means I don't need to replace the Battery inside my phone during it's lifetime.
job_shredder69
That is very likely already done by the charging circuit to protect the battery to an extend.