I have this problem as well, got my MacBook Pro M1 the day before yesterday, English and Mandarin are equally important for me so I have to switch between these two languages very often. At first, everything seems ok using globe/fn key switching, but yesterday suddenly it stops working, what I mean by 'stop working' is it doesn't respond at all and I found caps key does the work but I didn't change the system preferences. I checked system preferences and found globe/fn key is still set to switch between languages. I tried to restart the laptop but nothing changes. A couple of hours later, it suddenly becomes ok, the globe/fn did the work again... and today morning it was ok but now same problem happens again... it is quite annoying, I am writing feedback to apple, hope they will contact me...