MacBook Pro battery swelling in clamshell mode

I have a MacBook pro 15" retina, mid-2014. I use it in clamshell mode while connecting via thunderbolt to a dock that connects a larger monitor, hard-wired ethernet, a scanner and audio speakers. The monitor (and assume all of the other connections made through the dock) do not function with the power cord disconnected and the lid closed. They do function with the power cord disconnected and the lid open, although I always use it with the lid closed.

I bought the three-year Apple care with my initial purchase and had to replace a visibly swollen battery towards the end of that period, in 2017. The battery is visibly swollen again, leading me to believe that prolonged clamshell operation of a MacBook pro inevitably leads to a swollen battery. I have read other similar threads on this topic and there are posters who swear up and down that only defective batteries swell, regardless of how the computer is used. If that is the case, Apple is installing quite a few defective batteries in their computers.

I am getting ready to buy a replacement MacBook Pro. Has anything changed with regards to this issue, or is my only solution to periodically unplug the power supply from my computer? If the latter, how low should the battery get and how often should I do that? One poster said it should get down to 40% battery capacity. Some posters said it should be done once a month, some people say twice a week.

Thank you, Jesse