Q:

Magic Trackpad 2 became less responsive

I've been happily using Magic Trackpad 2 for exactly a year and a week (suspicious ;)) and today it started acting strange - I'm using only three gestures mainly (dictionary lookup, two finger scroll and pinch to zoom) and the pinch to zoom seems buggy - I'm not sure if that's the problem with the trackpad or the MacOS (10.12.6 - but I've been using that one for months now with no issues). 
So in short - before I was able to pinch to zoom all the time, right now I have to pinch and nothing happens and then quickly pinch again to actually zoom.  Most of the time it works 50% of the time.  I have only one MacBook and I'm wondering if I can somehow check if it is really an issue with my Trackpad or maybe with the OS itself? 
Also, a bonus question - what's the lifespan of Magic Trackpads?  I've been looking everywhere but couldn't find anything.  Can they last years?  I'm especially interested in Magic Trackpad 2 as it's the one I'm using. 

A:

There's probably a few things you could try (e.g. making sure the trackpad has a decent charge, resetting the NVRAM and/or SMC etc). 
However, the first thing I'd try is to reset both the macOS Bluetooth Device List and Bluetooth Controller.  
IMPORTANT: This will reset all connected Bluetooth devices, including any bluetooth keyboard or mouse, so all Bluetooth devices will need to be reconnected. 
Before commencing, you will need to have the Bluetooth icon showing in the menu bar.  If it is not there, open System Preferences > Bluetooth and enable the option Show Bluetooth in Menu Bar. 
Resetting the macOS Bluetooth Device List and Bluetooth Controller
Follow these steps:

Hold down both the Shift and Option keys and at the same time click on the Bluetooth icon in the menu bar.  Once the menu is showing, release the keys.      
From the Bluetooth menu, choose Debug > Remove All Devices
Hold down both the Shift and Option keys again and at the same time click on the Bluetooth icon in the menu bar.  
From the Bluetooth menu,  choose Debug > Reset the Bluetooth Module
Restart your Mac
Setup your Magic Trackpad 2 again
Setup any other bluetooth devices

Let us know whether this helps. 
As for how long it will last, the Magic TrackPad 2 was only launched in October 2015, so it's too early to say.  However, if the original Magic Trackpad is anything to go by, you should get years of service from it. 

A:

It's going to be a long shot, but:

Sierra has been superb all along,
at some point it started pushing these "Update to High Sierra" forced notifications,
after a week of these problems started to occur - first the whole Mac became less responsive, then the Magic Trackpad issue occurred and for the last two days I could not use the Magic Trackpad at all - the cursor became jumpy, even when charging,
NVRAM and SMC resets didn't help, jumpy cursor in safe mode as well,
I never installed anything in the last weeks, especially the trackpad issues happened all of sudden,
installing High Sierra fixed all issues listed above. 

I can't help but think it's all not a coincidence.  Maybe a funny way of asking people to upgrade? :/ 