In MY experience, with Lithium laptop batteries, if you leave the battery in and run off of mains - pluffing it into the wall, so kind of using the battery as a backup power supply if the mains power drops, that the battery does indeed degrade rather quickly. I have had them last 4 hrs when used alone, then run it for a few month on mains, then when I go back into the office and run off of battery, it only lasts 1.5 hours (same basic procesor load in both scenarios).
I love Anker, I am a total fan, and their use of 18650’s with regulators means that their products last - and they do, I have one almost 3 years old and all the ports work just fine, and it will still recharge my cell phone 3x easily. Now if trhey ever start to make laptop batteries with internal charging protection…