The Logitech MX Master 2S mouse is not yet compatible
with the new Logi Options+
software. Installing it will cause your mouse to have severe bluetooth connectivity problems, making your mouse unusable.
Despite this, a glitch is causing the software to being pushed out to MX Master 2S owners. If you get the notification to upgrade, or see the link to do so on your current software dashboard, don't do it!
Stick with the older Logitech Options
software you already have.
If you do inadvertently install the Options+ software, you'll have to plug in a USB mouse so that you can uninstall it, then un-pair your MX Master 2S, power it off and back on again, then re-pair it with your computer.