If you have a Mac and have seen a “Not Charging” warning when plugging it in to power, Apple last week released a support document that explains why.
Macs running macOS 10.15.5 or later have a Battery Health Management feature to preserve the life of the battery, and occasionally, the Battery Health Management option will cause the Mac to pause its charging for calibration purposes.
“Depending on its settings, your Mac might temporarily pause charging to help calibrate battery health management, a feature designed to improve the lifespan of your battery.”
Read more at MacRumors.com