The feature 8211; called Battery Health Management 8211; is in beta, but will launch as part of the macOS 15.5 update which is due to land soon. Apple has published full details in a very helpful guide. And you will be able to turn it off should you so wish.
Basically, the new feature will ensure your Mac doesn8217;t charge up to its maximum battery capacity in many cases 8211; but that8217;s not to say you won8217;t see the battery as being 8216;fully charged8217; in the macOS menu bar.
The new feature will charge your battery to the capacity it should be at to ensure the maximum lifespan. And it won8217;t treat all Macs the same 8211; it8217;ll depend on your previous history.
If you use your laptop plugged in most of the time, the feature will probably be useful on your Mac. Other factors such as temperature and even how demanding your needs are will play into it. For example, if you take your laptop on the move but constantly do resource-hungry stuff like video editing, it8217;ll treat your Mac differently than if you leave it plugged in but perform undemanding tasks.
The feature needs Thunderbolt 3 to work 8211; presumably because of the recording of previous charging data 8211; so it8217;ll apply to MacBook Pros made from 2016 on and the redesigned MacBook Air lineup first introduced in 2018.