Also, I rarely use my Mac battery. It's almost always plugged in unless it's in the kitchen showing me a recipe. smile
I ran a MacBook Pro that way until the battery swelled and I had to take it to Apple for a battery replacement (thank goodness for AppleCare).
This Apple Insider article offers some good information and tips on how to extend the life of your MacBook battery.
You've crossed the border into no man's land.
For many years, both Apple's and Battery University's guidance on how to treat your battery if you never unplug your Mac was to run it down once a month.
At least five years ago, both entities withdrew that guidance but never replaced it...went silent on the subject, but I continued the practice for lack of an authoritatively recommended alternative.
In the intervening years I've asked at least a half dozen "Geniuses" and AppleCare techs about it, and they've invariably told me what
they do but have been at a complete loss when I've said "That's nice, but what does APPLE say to do," at which point they've all said they'd file some sort of report, which has obviously been a useless exercise.
My 2015 MBP's battery swelled and was replaced, but there was a recall on the battery, so there's absolutely no reason to point at any particular factor as the cause of its failure.
Since I got the new battery I've changed my habit to shallow discharges - an hour a night - to give the battery more consistent use if nothing else, but I've got no idea whether or not I"ve done the right thing.
Apple certainly sells enough laptops for updated guidance to be in order, so I take their failure to provide it as an admission of ignorance.