Why does my Apple Pencil 2nd Gen keep dying?

The rechargeable lithium battery in your Apple Pencil (or used in any other device) has, IMHO, one major flaw ... and that is, if it is left partially or fully discharged for extended periods of time (think months), it loses its ability to either take a charge or to be fully charged.

FWIW, to provide a personal example. I misplaced and recently found my Apple Pencil 1st gen after not having been using it for over a year ... and guess what? It was completely discharged and wouldn't take a charge regardless of what I tried. The lesson learned? I put a recurring schedule item on my calendar to charge all of my little used (lithium-based) devices (spare wireless headphones, GPS devices, Kindle readers, etc.) every two weeks. Never had an issue since. You may want to consider doing something similar.