I am doing research on best practices for my lithium batteries and lifepo4 powerstation. There's some conflicting opinions and variation for cycle numbers.
Will leaving my things plugged in at 100% hurt it more than constantly unplugging at 80% and replugging at 20%?
Lithium chargers completely stop charging when the battery is full. Even if the charger remains plugged in, the battery will not be receiving power
That said, letting a lithium battery sit at 100% indefinitely is not good for it. If you can, reprogram the charger to fill the lithium to 80% instead, otherwise just let the battery sit at 100% as usual and just replace it after a few years when the runtime no longer is long enough for your application
I believe things are different for Lifepo4 which IIRC is more accepting of a float charge when full, although not ideal.