fwiw I’ve used 24/7/365 plugged in phones as AP’s in multiple locations for a decade or so now, never had an issue. Past few years I use the battery threshold to set them to 70% charge and they don’t move from this for months at a time.

What roasts the lifetime of my laptop batteries is compiling with gentoo, but again never an issue with catastrophic failure and I have 20+ years of experience with that as well.