Statistics are back in 2.1.8, however...
Two week statistics seem to be wonky - always a straight line (was also a straight line before statistics disappeared). One week and 30 days statistics seem ok.
I've had MalwareBytes BrowserGuard FireFox for several weeks and am very pleased. Statistics displayed fine until very recently and now Statstics (History) is Gone:
Version 21.7 Windows 10 FireFox 71.0 64 bit